Some users have gotten an error message similar to the following when attempting either to shutdown or restart Win XP:
STOP 0000009F, DRIVER_POWER_STATE_FAILURE
STOP 0x0000001E: KMODE_EXCEPTION_NOT_HANDLED
STOP 0x000000D1: DRIVER_IRQL_NOT_LESS_OR_EQUAL
TechNet and the Microsoft Knowledge Base have numerous articles discussing this type of error condition; for example, these. As a review of these articles will show, these are commonly device driver problems, but may also be caused by troublesome software (such as the notorious CrashGuard), or a problem in a system service. MSKB article Q262575 discusses a shutdown problem of this type, known to exist in Windows 2000 due to a resource (IRQ) conflict, if you have PACE Interlok anti-piracy software installed. This problem may occur in Windows XP as well.
Microsoft advises the following as one approach to these problems: Restart the computer. Press F8 during the restart and select “Last Known Good Configuration.” If you catch the problem when it first occurs (meaning you likely have installed only one or two drivers or new service), this will return you to a previous working condition. (Would System Restore accomplish the same thing? I don’t know, and don’t have a broken system to test it on.)
Microsoft reported similarly that these STOP code error message occur when Windows XP is trying to shut down devices. He says that he has seen this twice: once with Logitech Quickcam installed (with an unsupported driver), and once with a USB DSL modem that would hang if it wasn’t disconnected before shutdown.