its a dell optiplex desktop! windows starts up goes to my desktop and the all audio and video turns off! and the computer is still on! it started doing this slowly computer could be on for hours and would just lose all a/v! now it does it as soon as it starts up! the only thing i have done hardware wise is put a 19 hanns-g lcd on it it started doing this after i put this on! so i went back to the old 15"mag lcd and it still does it! i also got a virus that i removed rite b4 this started! I dont know what to do! i need to back up the pc! but cant see anything! is it the video card , mother board, harddrive?