I'm usually wrong about these things but is it possible that OP's machine is stuck with strange display settings? What if the resolution was set to something his TV or monitor are incapable of displaying?
OP, did you try rebooting into Safe Mode or at least the selection screen right before Safe Mode? I believe you would need to connect your monitor with the VGA cable for that to work. If that works, there should be an option to restore to the last settings that worked.
Ah, here we go. It's not exactly your situation, but you can get the idea from here [http://answers.yahoo.com/question/index?qid=20070907143645AATKY6y].