problem in booting microsoft xp

Very generic error, so could be 2,510 problems. That is how many hits google had.
1st What have you added hardware or software wise lately?
2nd make sure all cards are seated correctly.
3rd remove non essential cards if 1st doesn't help

Copy of one posting for a Sounblaster cause:
Posted by: gottaknow

After much searching, posting, re-installing, waiting for e-mails, I finally fixed the problem myself. I guess I was looking for something really complicated. I was going through all the windows configuration files. When I got to win.ini, I saw the entries under (Audio)

Disable MSmixer=True
SoundBlasterPCI=False

I changed it in note pad to:

Disable MSmixer=True
SoundBlasterPCI=True

Some said it was caused by the Blaster Virus, others said to remove SP1 (Don't think that is the cause)

If you can't even get into XP, which it sounds like and the card removeal does't help restore to an earlier version when it was booting. Assuming it ever did.
Just a few things to try first,
Lol

You may want to take a look at:
Generic Host Process Error Message and a Flashlight Icon Appear (821690) from Microsoft.com. Or simply look for 821690 on their search section. I'm not sure what else could be causing your issue other than what this page mentions as you didn't include much in your question to allow us to explore for other causes of your problem.