stop code unexpected_kernel_mode_trap 0x7F what failed CLASSPNP.SYS

Question

stop code unexpected_kernel_mode_trap 0x7F what failed CLASSPNP.SYS

Raymond Montebello 20

As Windows 11 approaches the login or just after login I get stop code unexpected_kernel_mode_trap 0x7F what failed CLASSPNP.SYS

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Answer accepted by question author

Ivan B 124.8K Independent Advisor

Hi,

That’s good to hear; I hope I was able to help. You can always count on the Microsoft Q&A community. If possible, please let me know if it was indeed TotalAV.

Thanks.

Raymond Montebello 20 Reputation points

2026-10-03T21:47:43.61+00:00

I have had no problems with the PC after removing total AV. I reinstalled all the windows updates and It’s been running for over 24 hours and I have rebooted the system multiple times.

I will delay reinstalling total AV actually considering not putting it back on as I’ve noticed the system running very slow with it.

thanks again for your help, Ivan.

3 additional answers

Your answer

Raymond Montebello 20 Reputation points

2026-10-03T21:47:43.61+00:00

I have had no problems with the PC after removing total AV. I reinstalled all the windows updates and It’s been running for over 24 hours and I have rebooted the system multiple times.

I will delay reinstalling total AV actually considering not putting it back on as I’ve noticed the system running very slow with it.

thanks again for your help, Ivan.

Answer 1

Raymond Montebello 20

When I was able to login and keep the PC running I reconnected the network cable and I have total AV performing an update and during this procedure the system crashed. So I performed a restore and it back dated Total AV only and the system seems to be working fine so then I removed program manually. I will try to reinstall at a later date. when I’m sure the system is running 100%.

Thank you for all feedback, I will check event viewer to see if I can pinpoint it to exact course.

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Answer 2

Ivan B 124.8K Independent Advisor

Hi,

This appears to be a driver-to-hardware connection failure. If you are unable to log into Windows, please try disconnecting all USB cables and other peripherals—leaving only the keyboard and mouse connected—and see if you can access the system.

If you are able to access Windows, please do the following: search for msinfo32.exe in the search bar, take a screenshot, and post it here so we can see the correct laptop model or desktop configuration.

Access the C:\Windows\Minidump folder, copy the files to your desktop, upload them to OneDrive or Google Drive, and post the link here for analysis.

Thanks.

Raymond Montebello 20 Reputation points

2026-10-03T01:56:56.53+00:00

Thanks ivan. That was the first thing I did took it down to minimum configuration. I also removed the latest windows updates, that didn’t seem to fix it, so I restored back to a restore point to 4 days ago and that seemed to fix it.

Time will tell as I was able to login and stay logged in for a minute or two before it crashed, unfortunately I wasn’t at the PC when it crashed so not sure what had loaded.
Ivan B 124.8K Reputation points Independent Advisor

2026-10-03T01:59:32.3333333+00:00

Hi,

Did you perform a clean boot when you mentioned the "minimal configuration"?

Then perform a clean boot

https://support.microsoft.com/en-us/topic/how-to-execute-a-simple-boot-start-in-windows-da2f9573-6eec-00ad-2f8a-a97a1807f3dd

Thanks.

Answer 3

UNEXPECTED_KERNEL_MODE_TRAP (0x7F) usually points to a hardware, driver, or related software problem. For this bug check, common causes include faulty or mismatched memory, failed hardware, kernel stack overflow, recently added hardware, or a recently installed/updated driver. CLASSPNP.SYS appearing as the failed file does not by itself prove that file is the root cause.

Try this order:

Check for recent changes
- If any driver, storage-related software, antivirus, or hardware was recently added or updated, remove it or roll it back.
- If the crashes started after a driver update, use Safe Mode if needed to remove or replace that driver.
Test memory
- Open Control Panel, search for Memory, then select Diagnose your computer's memory problems.
- After the test completes, open Event Viewer and check the System log for MemoryDiagnostics-Results.
- Faulty or mismatched memory is a documented common cause of 0x7F.
Check Device Manager
- Open Device Manager.
- Look for devices marked with an exclamation point (!).
- Open the device properties and review the events log, then update or remove the related driver if errors are shown.
Review Event Viewer
- Open Event Viewer → System log.
- Look for critical or error events at the same time as the crash to identify the device or driver involved.
Remove recently added hardware
- If any RAM, storage device, or other hardware was added, remove it temporarily and test again.
- Confirm hardware is compatible with the installed version of Windows.
Run manufacturer hardware diagnostics
- Run the diagnostics supplied by the PC or motherboard manufacturer.
- This is especially important for memory, storage, motherboard, and power-related faults.
Check firmware and driver updates from the hardware manufacturer
- Check for updates for BIOS/ACPI, storage controller, and network drivers from the device manufacturer.
If the system was overclocked
- Return CPU settings to default clock speeds.
- Overclocking is listed as a possible cause of this bug check.

If the crash began right around login, a startup driver or service is a strong suspect. If Safe Mode is available, remove recently installed drivers or software first, especially anything added just before the problem started.

References: