Why does my Windows 7 PC get a blue screen every time it starts up?

A blue screen on startup in Windows 7 is most often caused by 0x0000007B (INACCESSIBLE_BOOT_DEVICE), classpnp.sys, or iastor.sys errors. This happens after a BIOS SATA mode change, a failed driver update, or a corrupted boot sector. Boot from the Windows 7 DVD, run Startup Repair, or use the Recovery Console to run 'bootrec /fixmbr' and 'bootrec /rebuildbcd'. Also check that your BIOS SATA mode (IDE/AHCI) matches the original Windows installation setting.

How do I fix the atikmpag.sys or atikmdag.sys blue screen on Windows 7?

These BSODs are caused by the AMD/ATI display driver. Boot into Safe Mode (F8 at startup), download and run Display Driver Uninstaller (DDU) to completely remove all AMD driver traces, then install a stable driver version such as AMD Catalyst 15.7.1. On 64-bit Windows 7, also ensure your Windows is fully updated and that the AMD driver matches your GPU generation. Overheating can also trigger these BSODs — check GPU temperatures with GPU-Z.

What does STOP 0x000000F4 mean in Windows 7 and how do I fix it?

STOP 0x000000F4 (CRITICAL_OBJECT_TERMINATION) in Windows 7 means a critical system process or thread was terminated unexpectedly. The most common cause is a failing hard drive or SSD. Immediately run 'chkdsk C: /f /r' from the Windows Recovery Console. Check HDD health with CrystalDiskInfo — if you see Reallocated Sectors or Pending Sectors, back up your data and replace the drive. Also check SATA cables and power connectors.

How do I fix BAD_POOL_HEADER blue screen in Windows 7?

BAD_POOL_HEADER on Windows 7 indicates kernel pool corruption, usually from a driver bug, faulty RAM, or antivirus interference. Steps: (1) Run Windows Memory Diagnostic (mdsched.exe) or Memtest86+ to test RAM. (2) Boot into Safe Mode and disable/uninstall recently installed drivers or antivirus software. (3) Run 'sfc /scannow' to repair system files. (4) Check minidump files with WhoCrashed to identify the exact faulting driver. If a specific driver is blamed, update or roll it back.

Can I fix Windows 7 blue screen errors using only Command Prompt?

Yes. From the Windows Recovery Console (boot from Windows 7 DVD > Repair > Command Prompt), you can run: 'sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows' to repair system files, 'chkdsk C: /f /r' to fix disk errors, 'bootrec /fixmbr' and 'bootrec /rebuildbcd' to repair the boot configuration, and 'bcdedit /set {default} safeboot minimal' to force Safe Mode on next boot. These commands cover the majority of BSOD scenarios without needing a GUI.

Blue Screen of Death in Windows 7: Complete Fix Guide (BSOD, Stop Codes & Driver Errors)

Fix Windows 7 blue screen errors including 0x0000000A, 0x000000F4, atikmpag.sys, ntoskrnl.exe & more. Step-by-step BSOD troubleshooting guide with real commands

Last updated: March 1, 2026

Last verified: March 1, 2026

2,046 words

Key Takeaways

Most Windows 7 BSODs are caused by faulty or outdated drivers (especially GPU drivers like atikmdag.sys, atikmpag.sys, nvlddmkm.sys), failing hardware (RAM, HDD), or corrupted system files.
Stop codes like 0x0000000A (IRQL_NOT_LESS_OR_EQUAL), 0x000000F4 (CRITICAL_OBJECT_TERMINATION), 0x0000007B (INACCESSIBLE_BOOT_DEVICE), and BAD_POOL_HEADER each point to specific subsystem failures.
Quick fixes include running 'sfc /scannow' and 'chkdsk /f /r' from an elevated command prompt, updating or rolling back GPU/storage drivers, running Windows Memory Diagnostic, and using Startup Repair from the Windows 7 installation DVD.

Fix Approaches Compared
Method	When to Use	Time	Risk
sfc /scannow (System File Checker)	Corrupted system files, ntoskrnl.exe, ntfs.sys BSODs	10-20 min	Low
chkdsk /f /r	Disk errors, 0x000000F4, iastor.sys, ntfs.sys BSODs	30-120 min	Low
Windows Memory Diagnostic	BAD_POOL_HEADER, PFN_LIST_CORRUPT, RAM-related BSODs	15-30 min	Low
Driver rollback / update (Device Manager)	atikmpag.sys, nvlddmkm.sys, ndis.sys, iusb3xhc.sys BSODs	5-15 min	Low-Medium
DDU (Display Driver Uninstaller)	Persistent GPU driver BSODs (ATI/AMD, NVIDIA)	20-40 min	Medium
Startup Repair (Recovery Console)	Blue screen on startup, 0x0000007B, classpnp.sys	15-30 min	Low
Restore BIOS/UEFI defaults	0x0000007B, iastor.sys after BIOS change	5 min	Low-Medium
Clean Windows 7 reinstall	All fixes failed, persistent BSODs	60-120 min	High (data loss)

Understanding Windows 7 Blue Screen of Death (BSOD)

A Blue Screen of Death (BSOD) in Windows 7 occurs when the operating system encounters a fatal error it cannot recover from. The system halts, displays a blue screen with a stop code (e.g., STOP: 0x0000000A) and a technical description, then writes a memory dump file to disk. Understanding the stop code is the first step to a correct fix.

Windows 7 BSODs typically fall into four categories:

Driver faults: Buggy or incompatible kernel-mode drivers (atikmdag.sys, atikmpag.sys, nvlddmkm.sys, ndis.sys, fltmgr.sys, classpnp.sys, dxgkrnl.sys, dxgmms1.sys, iusb3xhc.sys, iastor.sys)
Memory corruption: Faulty RAM, bad pool allocations (BAD_POOL_HEADER, PFN_LIST_CORRUPT, APC_INDEX_MISMATCH)
Storage/filesystem errors: Disk failure, corrupted NTFS (0x000000F4, ntfs.sys, iastor.sys, 766f6c756d652e63)
System file corruption: Damaged OS files (ntoskrnl.exe, ntkrnlmp.exe, ntkrnlpa.exe)

Step 1: Capture and Read the Stop Code

Before you can fix anything, you need the exact stop code and the faulting module. If the BSOD disappears too quickly:

Right-click Computer > Properties > Advanced system settings
Under Startup and Recovery, click Settings
Uncheck Automatically restart under System failure
Set Write debugging information to Small memory dump (256 KB)

After the next BSOD, open C:\Windows\Minidump\ and use **WinDbg** or the free tool **WhoCrashed** to analyze the .dmp file. Look for:

The stop code (e.g., *** STOP: 0x000000F4)
The faulting module (e.g., atikmpag.sys, ntoskrnl.exe)

Step 2: Match Your Stop Code to a Root Cause

0x0000000A – IRQL_NOT_LESS_OR_EQUAL (windows 7 irql not less or equal) A driver accessed memory at an incorrect IRQL. Most commonly caused by faulty network drivers (ndis.sys, netio.sys) or third-party software. Update or uninstall the offending driver.

0x000000F4 / STOP 0x00000F4 – CRITICAL_OBJECT_TERMINATION (0x00000f4 windows 7, stop 0x00000f4 windows 7) A critical process or thread terminated unexpectedly. Almost always caused by a failing hard drive or SSD. Run chkdsk immediately and check SMART data.

0x0000007B – INACCESSIBLE_BOOT_DEVICE (0x7b windows 7, windows 7 blue screen 0x0000007b) Windows cannot access the boot volume. Triggered by BIOS SATA mode changes (IDE vs AHCI), missing storage drivers, or corrupted MBR. Restore BIOS defaults or run Startup Repair.

BAD_POOL_HEADER (bad pool header windows 7, bad_pool_header windows 7) The kernel pool allocator detected a corrupted header. Causes: faulty RAM, driver bugs, antivirus conflicts. Run Memory Diagnostic and update drivers.

PFN_LIST_CORRUPT (pfn list corrupt windows 7) The Page Frame Number database is corrupted. Points to failing RAM or HDD. Test RAM with Memtest86+ and run chkdsk.

atikmpag.sys / atikmdag.sys / ati2dvag.dll (atikmpag sys blue screen windows 7, atikmdag sys blue screen windows 7) AMD/ATI GPU driver crash. Very common on Windows 7 64-bit with AMD graphics cards. Fix: use DDU in Safe Mode, then install a stable older driver.

nvlddmkm.sys (nvlddmkm sys blue screen windows 7) NVIDIA display driver crash. Fix: DDU in Safe Mode, install a stable driver version, check GPU temperatures.

ntoskrnl.exe / ntkrnlmp.exe / ntkrnlpa.exe (ntoskrnl exe blue screen windows 7) The Windows kernel itself crashed. Caused by RAM errors, overclocking, or system file corruption. Run sfc /scannow and Memory Diagnostic.

BUGCODE_USB_DRIVER (bugcode usb driver windows 7) USB controller or driver failure. Update USB 3.0 drivers (iusb3xhc.sys), disconnect USB devices, and update chipset drivers.

CRITICAL_PROCESS_DIED (critical process died windows 7) A critical system process terminated. Run sfc /scannow and DISM to repair system image.

SYSTEM_SERVICE_EXCEPTION (system_service_exception windows 7) A system service threw an exception it didn't handle. Check the faulting module in the minidump — often a GPU or network driver.

Step 3: Fix AMD/ATI GPU BSODs (atikmpag.sys, atikmdag.sys)

This is one of the most common Windows 7 BSOD types:

Boot into Safe Mode (press F8 at startup > Safe Mode with Networking)
Download Display Driver Uninstaller (DDU) from Guru3D
Run DDU, select AMD, click Clean and restart
Download a stable AMD driver (AMD Catalyst 15.7.1 is known stable for Windows 7)
Install the driver and reboot normally

For the atikmpag.sys BSOD specifically on 64-bit Windows 7, also try:

Navigate to C:\Windows\System32\drivers\ and rename atikmpag.sys to atikmpag.sys.bak
Copy a known-good version from the AMD driver package

Step 4: Fix Storage-Related BSODs (0x000000F4, iastor.sys, ntfs.sys)

If your stop code is 0x000000F4 or you see iastor.sys or ntfs.sys:

Boot from the Windows 7 DVD
Select Repair your computer > Command Prompt
Run: chkdsk C: /f /r (replace C: with your Windows drive)
Check HDD health with CrystalDiskInfo (look for Reallocated Sectors)
If the BIOS SATA mode was recently changed, set it back to IDE or AHCI as it was originally configured

Step 5: Fix Memory-Related BSODs (BAD_POOL_HEADER, PFN_LIST_CORRUPT)

Press Windows + R, type mdsched.exe, press Enter
Choose Restart now and check for problems
Let the test complete (2 passes minimum)
If errors are found, reseat RAM sticks, test one stick at a time, or replace faulty RAM
For deeper testing, boot from Memtest86+ USB/CD and run for 8+ passes

Step 6: Repair System Files

For BSODs involving ntoskrnl.exe, ntkrnlmp.exe, classpnp.sys, fltmgr.sys:

sfc /scannow

If sfc reports it cannot fix files, use DISM:

Dism /Online /Cleanup-Image /RestoreHealth

Step 7: Startup Repair for Blue Screen on Boot

If Windows 7 shows a blue screen on startup (blue screen on startup windows 7):

Insert the Windows 7 installation DVD
Boot from DVD
Select Repair your computer > Startup Repair
Let it run — it will fix MBR, BCD, and missing boot files
If Startup Repair fails, use the Recovery Console to run bootrec /fixmbr, bootrec /fixboot, and bootrec /rebuildbcd

Step 8: Analyze Crash Dumps

Crash dump files in C:\Windows\Minidump\ contain the full technical details. Use the Windows Debugger:

Install WinDbg from the Windows SDK
Open the .dmp file
Run: !analyze -v
Look for FAULTING_MODULE, IMAGE_NAME, and STACK_TEXT

This will give you the exact driver or module causing the crash, enabling precise targeting of your fix.

Frequently Asked Questions

bash

# ============================================================
# Windows 7 BSOD Diagnostic & Fix Commands
# Run from elevated Command Prompt or Windows Recovery Console
# ============================================================

# --- 1. Check and repair system files ---
sfc /scannow

# If Windows is offline (Recovery Console), specify paths:
sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

# --- 2. Repair Windows image with DISM (online, requires internet) ---
Dism /Online /Cleanup-Image /CheckHealth
Dism /Online /Cleanup-Image /ScanHealth
Dism /Online /Cleanup-Image /RestoreHealth

# --- 3. Check and repair disk errors (chkdsk) ---
# Schedule for next reboot on C: drive:
chkdsk C: /f /r
# Answer Y when prompted to schedule on next restart

# --- 4. Fix boot records (from Recovery Console only) ---
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd

# --- 5. List installed drivers and check for unsigned drivers ---
driverquery /fo list /v > C:\drivers_report.txt
# Review the file for recently installed or unsigned drivers

# --- 6. Check Windows Event Log for BSOD entries ---
wevtutil qe System /q:"*[System[(EventID=41 or EventID=6008 or EventID=1001)]]" /f:text /rd:true /c:20

# --- 7. Force Safe Mode on next boot ---
bcdedit /set {current} safeboot minimal
# To revert back to normal boot:
bcdedit /deletevalue {current} safeboot

# --- 8. Disable automatic restart on BSOD (via CMD) ---
wmic RecoverOS set AutoReboot = False

# --- 9. Export minidump info (PowerShell alternative) ---
Get-ChildItem C:\Windows\Minidump\ | Sort-Object LastWriteTime -Descending | Select-Object -First 5 Name, LastWriteTime, Length

# --- 10. Check RAM with Windows Memory Diagnostic ---
mdsched.exe
# (Prompts to restart and test; check results in Event Viewer > System > MemoryDiagnostics-Results)

# --- 11. Uninstall a problematic driver via CMD ---
# Example: remove a specific driver by INF name
pnputil /delete-driver oem5.inf /uninstall /force

# --- 12. Roll back a driver to previous version (devcon tool) ---
# Download devcon.exe from Windows Driver Kit (WDK)
devcon.exe stack *VEN_1002*
# VEN_1002 = AMD; VEN_10DE = NVIDIA
devcon.exe rollback =Display

# --- 13. Check SMART status of hard drive (requires third-party tool path) ---
# Using wmic:
wmic diskdrive get status,model,size
# Full SMART: use CrystalDiskInfo or smartctl from MSYS2:
# smartctl -a /dev/sda

# --- 14. Read minidump with kd/cdb (Windows Debugger) ---
# After installing WinDbg/SDK:
cdb -z C:\Windows\Minidump\Mini010125-01.dmp -c "!analyze -v; q" > C:\bsod_analysis.txt
type C:\bsod_analysis.txt

# ============================================================
# END OF SCRIPT
# ============================================================

Error Medic Editorial

The Error Medic Editorial team consists of senior DevOps engineers, SREs, and Windows systems administrators with 10+ years of experience diagnosing and resolving OS-level failures, driver conflicts, and hardware faults across enterprise and consumer Windows environments. Our guides are validated against real crash dump analysis and Microsoft's own debugging documentation.

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