Hello,
Boot to Safe Mode, and uninstall Avast Anti Virus.
How to Boot to Safe Mode
By default when WinXP encounters a system failure, it reboots without warning. The setting that controls this can be changed:
Control Panel/System/Advanced/Settings (Startup & Recovery)/System Failure/Uncheck-Automatically Restart.
The Next time you get a BSOD, you'll be able to see the error message. I need that Message; word for word.