Couple of days ago my desktop crashed and when it restarted it said "Windows could not start because the following file is missing or corrupt: <windows root>system32/hal.dll. Please install a copy of the above file." I solved the problem using this: Hal.dll Missing Windows 7 - How To Fix Hal.dll Errors in Windows 7 and Windows Vista. This problem only happens on Windows XP but I'mm running a year old clean install of Win7 Ultimate. What could be the cause of this problem? Thanks.