computer rebooting

computer boots up normally then once windows is just starting to run it displays “can’t load vsmpsgty.dll” and then reboots. it won’t stay on long enough to do anything to or really read anything other than that. safe mode works fine. i was reading on this site on how to disable the system to reboot after error. but couldn’t flesh it out. previous to this we installed windows mediacenter version of xp. about three weeks ago with no problems but then it started finding new hardware something for the pci slot and then a buss controller. i installed all of the software drivers for the computer and its worked great till now.

any thoughts