This has just started happening to me. I don't think windows updated and I have used two different restore points to no avail. I am running a 8800GT. Everything works fine until after the windows loading screen and then the no signal input comes up on the monitor and it cuts out. My PC is still running and I can still log into windows even though I can't see anything. I'm using XP and switched my PC off normally last night so I doubt my GPU randomly fried. And it runs fine in safe mode. A virus scan has revealed nothing. Going to roll back my GPU drivers now.