maybe you should check your event viewer (administrative tools) and see if anything seems strange there in the logs maybe a driver problem will be there (may help to track when the problem started) .. Run chkdsk /f to check drive for simple drive error or something like that. This could be caused my many things, (bad driver,memory error, hard drive) You could also try SFC /scannow command to check all protected system files for corruption. Hope this helps a bit!
