computer won't boot past POST

Ok, this is a really weird one. All was going fine one day and suddenly my pc blue screened while just sitting idle. Then it blue screened every time I tried to restart. I figured I would just whip out the xp cd and reinstall. It blue screened half way through several times but with different numbers every time. I've moved it to a different room where I can access it more easily and now it will boot through POST and black screen. If I try and install xp, it makes it to "inspecting your computers hardware configuration" and locks up there. I ran a 24 hour memory test with Linux Knoppix and came up fine; even tried memory out of another pc. I've used two other processors that all work fine in another pc. I've tried multiple video cards with no luck. I've run all 3 hard drives in another pc with no problems. I've tried booting with only one drive, two drives, no cd-rom and I've even gone througha large ammount of cables that all tested good.
Now, here's the strange part... I tested the cmos battery and it read right at 3v so I know it's good, but if I unplug the power it resets everything. The other odd thing is I've always config'd my drives as master/slave; I just never got in the habbit of using cable select. Now, all of the sudden, with the drives set to master/slave, the bios will not recognize the drives at all on the primary or secondary IDE but, if I set them to cable select they show up instantly where as the hd and cd on the secondary are fine on either channel. It won't recognize a single drive set to master either, just with cs.
I have several bootable cd's; a diagnostics tool disk, western digital lifeguard tools, Knoppix STD/4.0/5.0, Linux SUSE and they all boot from cd and run flawlessly. I had two PII 400's in my shop with Linux mandrake and Red Hat (pre-enterprise) so I figured I would slap one of those drives in place of my primary and whaddya know, they both worked. I ran each of them for over an hour without any problems. Could the motherboard have just decided it's had enough of windows? It seems to work with everything else. Right now I have "everything" unplugged from the mb. The only thing I don't know how to test is the output wattage on the power supply. All the voltages read fine. I can't really think of anything else at the moment. Any suggestions or advice would be greatly appreciated. Thanks

 

Hi and welcome. I'd try a new power supply.

 

I'd try a new battery, too. Reading 3 volts doesn't show what the battery output is under load.

 

I have several new batteries to swap out but the power supply is what I will probably have a hard time getting a hold of. I will definitely check the battery contacts and make sure they're clean. I was just goofing about it getting tired of windows. It just seemed odd that all of the sudden everything will work except windows. I have to go feed the fish and birds so I will post later with progress. thanks