Problem with restarting computer.

[F_G]

I have IBM TP T20 2647-81G with the last version of BIOS.
There was WINDOWS 98SE ENG, which operated without problems, then I setup
WINDOWS XP SP1.
I setuped all drivers, and system is very stable.
But there is one
problem: when I want to restart my computer, it stops working
on the stage of loading windows, so I do restarting of computer by switching it off/on.
Then I setuped service pack 2, but this problem saved.
In WIN 98 there was`t this problem.
How can I solve this problem?
Thank you.