I think I have the same damn problem. A friend of mine built a computer tower for me, and it was working for him. He mailed it to me, it suffered some superficial damage (dent in the exterior and plastic attachments which attach the face of the tower to the body are all broken, so that the face is only attached by the wires that feed the power/reset buttons). Anyways, I tried to use the new system (P4 1.8?Ghz, WinXP) with my old monitor and, although the system appears to be booting (all fans come on and beeps), my monitor remains blank with power.
I called a support person for my monitor and she suggested that the monitor might not be compatable. So I've since tried my new system with a newer Dell monitor and I have the same problem. When it's plugged in the monitor light goes yellow. When I unplug it, it goes green and says "no signal."
My new system also has a GEForce4 TI4400 graphics card and I suspect this might be part of the problem, but it seems to be plugged in properly and the fan on it is running.
What else can I do?
What is this problem plaguing us?