My comp was suddenly shutting off during movies, music and internet browsing. It gen didn't shut off while standing still. I used the Dell OS CD to erase the partition and format NTFS (reg, not quick). During the menu's before the formatting and during the formatting, it continue'd to shut off. Now I don't have an OS. On another comp, I burned two CDs, one is Window MEm Test and the other is memtest. The computer passed the Windows mem test on all 11 counts of the adv scan. It keep restarting during the other CD, with memtest. Neither memory testers show an error while they are running. Both are run in default mode, as configured when I burned the ISOs the their CDs. I ran the built-in diag tool in the Bios, but it could only run half the tests, because the diag utilies on the HD are erased. I don't have the drivers and utilities CD that it asks for. Is this a memory prob, power supply, or what? I don't really have money to take to a repair shop or buy parts without knowing the prob. Let me know if you need any more info.