I am running Windows XP on a P4 1.5 GHZ with a GeForce 2 MX. It is working fine. However, I am trying to upgrade to a GeForce 4 4400. When I replace it with the new one, there is no POST beep and there is absolutely nothing going on the monitor. I get a black screen, nothing else. The computer seems not to be booting. It looks to me that is is not a software problem, but rather a hardware problem. Does anybody have come across this problem? Does anybody know how to fix this?