BNG
I have not experienced any problems with Avast in so far as drive partitions restored from images (in my case using Acronis True image) if that is what you are asking, however since starting to use Avast, I have only restored operating partition images back to the drive they were made from, and not to a different drive. I don't replace the MBR or track 0 during the restore operation. You have not said what you used to copy the partition image to the new drive and so I don't know whether you replaced the MBR or track 0 in the process.
You also didn't answer my query about whether your bios supports 48bit LBA. You did say you are using XP, however it's my understanding that XP didn't support 48 bit LBA until SP1, and you didn't mention what level of patches you are up to. Depending on exactly what the situation is, simply limiting the size of a large drive to below 137GB in an installation that doesn't suport 48bit LBA may not guarantee that loss of data will not occur and it is usual to employ one of the available software solutions.
I too don't understand how a problem to do with the Web scanner terminating can still occur when you have uninstalled the program.