Only questions at the moment, no advice yet. The answers might be clear to YOU, but please remember WE don't know unless you tell us.
1. What program do you use to backup?
2. Can you fully access the drive (put files on it, delete files) using My Computer or Windows Explorer?
3. What version of Windows XP do you have (like Pro SP1 or Home SP3)?
4. Can you see anything about the error in event viewer (after the reboot)?
5. What does chkdsk say about the drive?
I just replaced my old 250gb drive with a new 1TB drive, i used the seagate discwizard to copy my old drive to my new drive(samsung). For some reason every time I try and backup any data on my tb drive using the XP backup utility it starts then suddenly reboots. Anyone have any advice on this issue?