Asus P4P800S-X won't post or display video

Hi,

This is a new board, P4 2.4A processor with a PC2700 512MB memory module in bank 1, an AGP GeForce2 AGP 64M 4X video card. The case has a 400W power supply. These are the only components installed so far.

When I first powered up the machine, I got a post then video. I went into CMOS to change the time and disable quick boot so that I could see a memory test. I also changed Plug and Play OS to Yes since I intend to install XP. When I saved and exited, rebooting showed no video or post. Since then, when I power on the power supply, the power indicator on the board lights up and the keyboard lights up brightly then stays very dimly lit. When I hit the power switch on the case the processor fan spins, but I get no posts and no video. I tried to reseat the memory, move it to a different bank, reseat the video card, and try a pci video card and nothing changes.

Can anyone help?

OK, here is the weird thing. I found that when the mouse is connected to the board, the system won't post or boot. When I remove the mouse, It does post and attempt to boot, but I have no OS installed. I tried different mice to see if it was a bad mouse and had the same problem.

I intended to install XP on the computer, so I need the mouse. I decided to do the install as far as I could with the keyboard only. After getting to the point where a mouse was required, I shutdown the computer. I connected the mouse and the computer posted, booted from that point on with no trouble so far. I re-installed the OS with the mouse attached and have had no other occurrences.

I can't explain it, but the problem went away. I wish I understood why.