Computer keeps rebooting itself.

Hi, and help please!
My HP Pavilion a220n PC (AMD Athlon XP processor 2600+ 2.08Ghz) all of a sudden just keeps rebooting itself. It will get to the "Windows XP" loading screen (with the blue box scrolling left to right), then it will go blank and then restart. It never makes it to the Windows Login screen. When I try starting it in "Safe Mode ", the list of loading drivers will freeze at "agp440.sys" and then restart again and again. When I "Disable automatic restart on system failure ", it will give me the beloved Blue Screen Of Death, which says:

"STOP: c000021a {Fatal System Error} The Session Manager Initialization System process terminated unexpectedly with a status of 0xc0000139 (0x00000000 0x00000000). The system has been shut down. "

When that happens, I can only manually reboot. Before, it "...terminated unexpectedly with a status of 0xc000026c... ", but after going into Windows Recovery Console and replacing some of the recently installed Hotfixes (including #890859) with the original system files, the status changed to "0xc0000139 ". Still, it didn't fix the endless cycle of restarting and Blue Screen Of Deaths.

If anybody has any idea what's going with my computer and how to fix this problem, it would be much appreciated. Thanks!

 

Hi,
I recently had the fun of trying to fix a computer with pretty much the same problem and eventually had to do a "Reinstall/Repair " and for now all is well.

The aggravations that followed were reinstalling all the Microsoft Windows Updates, etc and if you have Windows Xp,and the CD has SP1 on it, you then have too at some point download the SP2.

All the above is a little bit time consuming, so if you end up doing a "Reinstall/Repair" set aside a few hours or so (FYI).

Good Luck.