If the system failure is hardware related the cause could be anything from heat related such as overheating video card, bad sata cable to a dying monitor. It's hard to say, but basically there is a MB, CPU, RAM, video card, HD and PSU. Or course spare parts would be neded to troubleshoot the system hardware. If software related, perhaps a system driver is causing the system shutdown. Maybe consider updating the video card driver, MB drivers and other system drivers. Alsoinstall latest SP3 and all OS updates from MS. You could always do a repair install and bring the OS back to the point of the CD used to perform the repair installation of the OS. Beause you are loosing the picture, which video card driver are you using? The driver on VC CD is the one the card was tested to work properluy with. One other thing is to boot into safe mode and let it sit a while. If the system shuts down there it is likely hardware related.