How to Fix Bug Check 0x7F: UNEXPECTED_KERNEL_MODE_TRAP

The UNEXPECTED_KERNEL_MODE_TRAP bug check has a value of 0x0000007F. This bug check indicates that the Intel CPU generated a trap and the kernel failed to catch this trap.

The error is usually triggered by two situations that occur in the kernel mode: either the CPU generated a condition that the kernel is not allowed to catch or the condition is an unrecoverable error.

The most common cause is hardware failure, mostly due to faulty or mismatched memory. There can be cases when faulty software currently installed on your computer can also make this error appear.

If you recently added hardware to the computer, remove it to see if the error recurs. If existing hardware has failed, remove or replace the faulty component. Run hardware diagnostics that the system manufacturer supplies to determine which hardware component failed.

Check that all adapter cards in the computer are properly seated. Use an electrical contact treatment, available at electronics supply stores, to ensure adapter card contacts are clean.

If the error appears on a newly installed system, check the availability of updates for the BIOS, the SCSI controller, or network cards. These kind of updates are typically available on the Web site or BBS of the hardware manufacturer.

Confirm that all hard disk drives, hard disk controllers, and SCSI adapters are compatible with the installed version of Windows. For example, you can get information about compatibility with Windows 7 at the Windows 7 Compatibility Center.

If the error occurred after the installation of a new or updated device driver, you should remove or replace the driver. If, under this circumstance, the error occurs during the startup sequence and the system partition is formatted with NTFS, you might be able to use Safe Mode to rename or delete the faulty driver. If the driver is used as part of the system startup process in Safe Mode, you have to start the computer by using the Recovery Console in order to access the file.

Also restart your computer, and then press F8 at the character-based menu that displays the operating system choices. At the Advanced Options menu, select the Last Known Good Configuration option. This option is most effective when you add only one driver or service at a time.

Overclocking (setting the CPU to run at speeds above the rated specification) can cause this error. If you have overclocked the computer that is experiencing the error, return the CPU to the default clock speed setting.

If you encountered this error while upgrading to a new version of the Windows operating system, the error might be caused by a device driver, a system service, a virus scanner, or a backup tool that is incompatible with the new version. If possible, remove all third-party device drivers and system services and disable any virus scanners before you upgrade. Contact the software manufacturer to obtain updates of these tools. Also make sure that you have installed the latest Windows Service Pack.

The most common cause of this error is a faulty RAM module that periodically gives read/write errors. If that’s the case, then it is advisable to scan the system memory with Memtest86+ and replace the faulty RAM module.


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