Check cpu temps in bios if not high I would run memtest
http://www.memtest86.com/ download create a cd then boot from cd ensuring your boot order is correct,If this passes then run prime95
http://www.mersenne.org/freesoft.htm this will then have tested your memory and cpu,If this test runs for say half hour your cpu is ok
Then maybe try a repair install using you xp cd,if all else fails try a reformat and reinstall
It could be something simple like a program at boot up,ive seen norton do similar
And although you have your own welcoming thread I
you here
