After updating my Windows 11 PC and Lenovo Vantage, I've been experiencing unexpected restarts, accompanied by error messages like 'IRQL_LESS_OR_NOT_EQUAL.' The error screen indicates a problem and suggests restarting, showing stop codes such as DRIVER_VERIFIER_IOMANAGER_VIOLATION (0xC9) with the failed driver being AcpiVpc.sys. I'm looking for solutions to stop these random restarts. I've also included some screenshots showing the errors I'm encountering.
5 Answers
It sounds like you might be dealing with a hardware issue. I recommend running a full suite of tests using OCCT on your RAM, CPU, and storage to check for any stability problems. Sometimes, issues like these can stem from faulty hardware, so it’s good to rule that out first.
It could be a combination of outdated power management drivers and a BIOS mismatch after the Windows update. If you've enabled Driver Verifier, make sure to turn it off as it could contribute to additional crashes. Checking for BIOS updates might also resolve the issue.
The AcpiVpc.sys file is related to the Lenovo Virtual Power Controller, which can cause issues if the driver is outdated or incompatible. Here’s a fix you can try: go to Device Manager, find the Lenovo ACPI-Compliant Virtual Power Controller, right-click, and choose 'Roll Back Driver.' After that, try setting your Windows power settings to 'Performance Mode' and disabling sleep and fast startup.
If rolling back the driver doesn't help, try uninstalling the ACPI-Compliant driver entirely through Lenovo Vantage, then reinstall it. Another option is to boot into a live Linux environment and run some stress tests there. If everything works fine under Linux, your problem is likely software related.
Make sure that after troubleshooting these issues, you run the Windows SFC scan. If it shows that the files are intact, it strongly suggests the problem lies with the drivers rather than Windows itself. If the crash logs show specific drivers involved, that's a key clue as to what’s causing your restarts.

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