I use system restore/system backup often and have for some time. The backups and system images which can be restored to any drive are kept on an external drive, but this is now far off topic.
This just started last week and I believe it to be a false positive from avast. I’ve sent the files to avast and there is at least one other person experiencing this as determined by a google search.
If this is an actual virus then why is avast not finding the root cause (i.e., no virus until the backup is complete… if there was something being added to the catalog that was a virus why can’t avast identify it)
Also as I look at the forum in the last couple of days it seems quite a few people are now experiencing false positives.