Are you sure it's the monitor and not the video card? When the computer is first turned on and it goes through the post every video card uses a generic driver to start. And it sound like yours is going bad.
Also if you have access to another monitor try pluging that one in and see if you get the same problem, if so I'd say video card. Another also, check the monitor settings and make sure no one has changed them on you (for a prank).
Edit: Just thought of another thing to look for, make sure the monitor is pluged in all the way. Some times they can come lose.
Last edited by mrrangerman; 03-07-2008 at 02:53 PM.
Reason: add info