XP reboots after SP2

[LLKing]

My friend installed SP2 and now when he trys to start his computer it reboots itself overs and over. It gets the splash screen, then a black screen, then a black screen with a cursor, then half of the time ZoneAlarm will fail, and then it reboots with the error code c00021a. It does this in safe mode too. Microsoft suggests booting into Safe Mode with networking but it reboots before I can get rid of whatever they say to get rid of. I read elsewhere that I should put in the XP cd and boot from the disk but, with the bios telling it to boot from the cd first, it will not boot from the disk. What can I do to fix this? Please help ASAP because my friend makes money through his computer.

 

[sswingle]

Boot from the Windows CD, go into setup. Press Enter to install, F8 to agree to license. It will tell you windows is already installed, push R to repair. Sit back and let it do its thing. When it restarts, you will have the Windows back without SP2.

 

[Jayczar]

**if **you are using a P4 Prescott make sure that your motherboard
has the latest BIOS to update the microcode. The problem you are
having is common with SP2 and Intel prescotts. Article