After Re-formating Windows XP, My computer started randomly rebooting, particulary but not limited to, youtube videos and while playing songs in Windows media player. IMO, the first thing you should do is try the obvious things first before trying a MEMTEST and or posting Mini-dumps and such. Such as software and hardware conflicts and drivers issues. Or even switchin some basic settings such as Graphic acceleration. 1. Turn off Automatic restart by, Startmenu>Rightclickmycomputer>Properties>Advancedtab>Under startup and recovery click setting>Uncheck Automatic restart under system failure. A) This will take you to the BSOD so you can see what kind of error message your getting. 2. Look in the Event viewer by, Startmenu>Right click on my computer>Manage>Event viewer>System A) This will give you a more detailed description of the error your getting. Then Google it! Driver_less or Not_ Equal, is more than likely a Driver issue. Since my computer was primarily rebooting when watchin youtube videos it only made sense it was some sort of Graphics Driver issue. The thing is, was, after reinstalling windows, Both the Audio and Video drivers were missing. Now its easy enough to Diagnos the Sound Driver through the Device Manager In addition to no sound; But things get a little more difficult when it comes to the Video Drivers. For some reason there was no yellow ? in Device Manager under DISPLAY ADAPTERS. Turns out, when I went to update or install my video driver, I Inadvertantely installed the wrong one, which in Effect, lead to more of a Mystery/Confusion. A) Right click on destop>Properties>Settingstab>Under display to view your video driver. Solution: I Booted into Safe-mode(not sure this had anything to do with it) and uninstalled my Display Adapter, then rebooted into Normal mode and Viola! the Newfound hardware wizard took over from there, and proceeded to install the correct Graphics driver. Problem solved! PS. Was running a 9600/9550x1050(version 5.1021) When I should of Installed a RADEON 9600 Series. Good luck!