A7N8X Mobo locking up at the beginning of POST (help)

Hi,
I have a home built computer that is a few years old. Recently I put it in a new case and it was working fine for a few weeks. Then all of a sudden it stopped recognizing one of my RAM chips so that I only had 512mb instead of 1gb. So I took it apart and reseated the ram thinking maybe I knocked it or something when I changed cases. Well, when I went to boot up It decided to lock up at the splash screen of the POST. I tried unplugging everything and trying different RAM combinations on the motherboard and it still did the same thing. I even reset the CMOS but still no luck. I recently bought a new stick of memory, 1gb, and it seems to be doing the same thing. Is it my mobo, psu, memory or something completely different?

SPECS
mobo - A7N8X Deluxe
cpu - amd athlon xp 2400+
mem - 2 512mb pc2700 elixir (original mem), 1gb pc2700 pny (new mem)
Graphics - geforce 5750
PSU - 480WATT Ultra x-connect
HDD - 1 60GB EIDE, 1 160GB SATA

Let me know if you need any other info.

Is there any post beeps

Yes, it does the usual one beep meaning its all ok and then it just stops.

Have you tryed plugging only the 512 memory stick in

yes, and it still does the same thing

http://www.techspot.com/vb/topic53866.html

Test ram. Memtest link on my sig

I got my memory tested by the geek squad and they said it was bad but they also mentioned that the memory ports on my motherboard could be bad. Any suggestions?

I also managed to find my old memory stick and I tried that but alas still no luck.

I suppose realy the only thing left to be causing the problem is your motherboard.

Agree. Swap out the mobo and see what happens.