I have a Compaq running XP SP2 (currently unable to update, working with MS on this issue), and when I attempt a scan with AVG, it gets to the same place each time, near the beginning of the scan in the registry, and the system reboots. After reboot, a message comes up indicating there was a fatal error and prompts me to send the report to MS. When I do, it comes back stating there was a Blue Screen and give me three things to try, updating drivers, virus scan, and chkdsk. I am able to run the AVG scan in safe mode, and a chkdsk gave up no errors. I have not tried the drivers yet, but wanted to get some feedback on this since sometimes updating drivers can cause other issues. May posts point to heat issues, but since I am able to run the scan in safe mode, and I have been able to do defrags and other disk and cpu intensive items without issue, I think it is isolated to AVG. My system is a Compaq Presario S6500NX. Thanks.
Have you tried a chkdsk on the hard drive to see if there are any bad sectors as advised? This could isolate the problem as running the scan in safe mode may well cause AVG to miss the sector where the problem is.
Give it a try and let us know the results.
Snibborg