i have used avast for about 18months but in the last week i haven’t been able to do a full scan as it never - ok after 17 hrs - gets pass 1% - didn’t something change in the program?
Maybe the HDD has some other problem? Or the filesystem? Have you tried with chkdsk / scandisk?
i did a chkdsk no problems found and started the scan again - it’s been 1.5 hrs and it is still at 1%