Let me start by posting my system specs.
Jetway 939GT4-SLI-G Mobo
Athlon 64 3800+
2Gb Ram (2x1Gb GSKILL 6400)
EVGA GeForce 8600GT
WD Caviar SE16 320GB SATA HD (new)
Hitachi 160GB HD (old)
550W PSU

Anyway for the past week or so my computer would crash randomly when I was gaming or downloading things. It would click, give me a few seconds to work, and then completely freeze up. It would take a few restarts to fully reboot back to windows. Anyway I figured it was a HD problem so I got the new Western Digital and spent some time installing Windows XP and drivers for everything else. Everything seemed fine until I was installing software for my Zune and my computer must have crashed when I left the room to wait for the install. Since then it crashed once while web browsing and installing other programs and hangs for a few seconds randomly.From experience I would guess that this is my PSU's fault, but when my computer crashes, my BIOS does not detect my new SATA hard drive. I restart my computer a few times to no avail; however, if I turn it off and unplug it for a while (a minute or so) my BIOS detects my hard drive and I'm up and running. If anyone has any suggestions or answers to address my problems please answer because I am clueless at this point.
Thank you in advance