Computer restarting during boot, Will start up with boot disk

[mangork]

Running windows xp 64 bit pro. Everything worked fine yesterday but today I cannot get it to boot properly. After the POST screen I get the windows logo with a loading bar like normal, but then after that it just goes black and I can hear the drives running for around 30 seconds before the computer restarts. I used Hiren's Boot CD and can start the computer in linux off of that. Unfortunately I lost my windows xp CD's in a move and I have no idea if it is possible to get new xp 64 bit pro CDs from anywhere these days. Any ideas?

 

[nhasian]

to obtain a replacement disk, telephone the Microsoft Order Desk at (800) 360-7561, and request a replacement for your lost or damaged disk.

 

[mangork]

What should I do when I get a replacement disk?
Edit: I disabled the automatic restart and got the following error on a blue screen
"Stop: c000021a {Fatal System Error}
The Session manager initialization system process
terminated unexpectedly with a status of
0xc000026c (0x00000000 0x00000000).
The system has been shut down."