Hey everyone-
  By brother brought me his problem PC to look at. Windows XP (notsure if SP2, can't get there yet)
It is AMD Athlon 950MHz - 256MB RAM.
When I fire it up, everything loads up fine, it will sit for a couple of minutes, then there's a quick blue death screen flash and it shuts down.
The other odd part, once it comes up, if I try to open anything, that instantly kills it.
The blue screen is much too quick to read.
It will run in safe mode, and I have ran multiple AV's and spyware scanners in safe mode, only 1 scumware prog found and fixed.
The hard drive chugs along pretty good after boot before the blue screen.
One more note, I ran the MicroSoft memory test (bootable disk downloaded from them) and that passed.

My main question, does WinXP log the blue screens o' death?
If so, where do I find that, maybe it will shed some light.

Any ideas will be appreciated.

edit: It is running SP 1, I'm sure I won't be able to update without it dying on me.

Have you tried booting into safe mode?  Hit F8 key as you start the machine.  A menu will appear and have a list of options to select from.  Select start in Safe mode.  If you are able to run for a while in safe mode, scan the system for adware, viruses, etc..  If you select safe mode with networking, you will be able to download scanners such as ad-aware, spybot, torjanhunter and anti-virus such as AVG or Avast if there are none on the machine.  Let us know.

Sorry, didn't mean to post my prior post.

There should be a log entry of some sort.

Your logs are available here: 
To open Event Viewer, follow these steps:
1.   Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
2.   In the console tree, click Event Viewer.

The Application, Security, and System logs are displayed in the Event Viewer window.

Excerpted from : http://support.microsoft.com/default.aspx?scid=kb;en-us;308427&sd=tech#XSLTH3126121122120121120120

And you can look up more info on errors here (have source of error and error id handy):
http://www.microsoft.com/technet/support/ee/search.aspx?DisplayName=Windows%20XP%20Professional&ProdName=Windows%20Operating%20System&MajorMinor=5.1&LCID=1033

I've seen a faulty device driver do this as well.

Thanks,Organ_Shifter, that stopped the screen o' death long enough to get the info.
Now I need to figure out what the H it means.
0x0000008E (then dozens more in parenthesis)

edit: looks like a memory problem; I ran MSofts memory test the other day, and it passed repeatedly, hmm. I will troubleshoot memory modules later. I may try a whole different single stick. I'll report back; Thanks.

Still working on it (between entertaining my 2 year old).
Here is a snapshot of the blue death screen, in case it helps:
(sorry, it is a photo of the monitor, little blurry)

Thanks, php.
Looks like the fix is updating to SP2.
I will try updating in safe made tomorrow, getting a little late now.
If I start it, I know I'll be up until 3AM and regret it at work tomorrow.