Problem with my laptop and Windows XP

having a problem with my laptop. Two weeks ago I lost my profile from the machine which was more than a bit annoying. I’ve got the new profile that was created for me almost back to where my old profile was but I was wondering if anyone knew

How to get my old profile back? (Cause when I look at the accounts on the machine there is 3GB for the backup of my old profile but I don’t know how to make the backup my local profile)

Also the biggest pain is, on my laptop sometimes the machine will suddenly reboot. Closes all the applications and then reboots. Really beginning to annoy me. It doesn’t do it if I’m working on something but if I leave it for a second, it closes the machine down…very annoying.

By the way this is using XP, anyone any ideas?