I had the same problem...The funny thing it was in my bios where it gave the option of where the start up was to first look for video, agp, pci or onboard. When it was going dead it was because I had the startup look for the vid still in the pci slot. Once I set it to agp all was well. If this ain't the prob then try another vid card if ya have one. sounds like it might be shot. Does the computer stay running even though the monitor is in sleep mode?