I have a HP Pavilion 502n Desktop. Memory is maxed at 512 mB. I am trying to install a new video card (ATI Radeon 9000 - PCI), and after installing and rebooting, my PC beeps at me 3 times and the screen says there is no input, either VGA or DVI, and goes black. I tried to disable the onboard video before installing and I get the same behavior. Is it a compatability issue? The motherboard has 3 PCI slots. Thanks.