My Pc keeps crashing, it can happen at any time, but is more prone to it when I am loading new programs or playing games, but really can happen for no aparant reason. It either just freezes on whatever it is doing or re-boots, first to a blue backed screen saying that Windows had been shut down to prevent further damage and gives this error message; "DRIVER_IRQL_NOT_LESS_OR_EQUAL" and then after restarting gives this error message; BCCode:d1 BCP1:00000067 BCP2:0000001C BCP3: 0000001 BCP4 FFFFFF OSVer 5_1_2600 SP:2.0 Product 768_1. When it does the disk scan I often (but not always) get errors come up warning me of Cross Matched files that Windows fixes and lists of several programs where "the first allocation unit is not valid and will be truncated, these programs often then stop working. I have done several restores, disk and surface scans and found nothing. Anyone know what could be causing it?