Hello more computer savvy than I. After Avast home gets done with a scan, most of the billions of files it scans say next to them in the report “unable to scan”. I’m not sure what that means. We also have several worm, trojans and other odds and malware ends. My 15yr old goes to umpteen game and message sites and on and on. None of these seem to be repairable. Avast says send to chest and after a few tries they usually go. How do I clean these off my system. I assume they are imbedded in the registry? I’d like to do this. My better half gets mad when I talk about wiping the system clean and having to backup stuff of delete things. And besides, my software came on the system, I don’t have a lot of cds’. Anyway, thanks for any wisdom.
Matt
I won’t worry that much. The files could be in use and can’t be scanned, the files could be password protected (generally other security programs encript their signatures/files), etc.
Can you post the ‘most’ common paths of these files?
The majority of the trojans can’t be repaired as the entire file is a virus. They can (and this is enough) only be deleted.
Are you using Windows XP? Can you schedule a boot-time scanning? Start avast! > Right click the skin > Schedule a boot-time scanning. Select for scanning archives. Boot.
Welcome to avast forums 
Many programs (usually security based ones) password protect their files for legitimate reasons such as AdAware and Spybot Search & Destroy, there are others (and avast doesn’t know the password or have any way of using it even if it did know it).
When you run scans with the above programs and you delete harmful entries that they detect, a copy is kept (in quarantine/restore/backup) in case you need to reverse what you did. These are usually password protected, you should do some housekeeping and delete old backup/recovery/quarantine entries (older than two weeks or so), this will reduce the numbers of files that can’t be scanned.
By examining 1) the reason given by avast! for not being able to scan the files, 2) the location of the files, you can get an idea of what program they relate to. You may need to expand the column headings to see all the text.
Files that can’t be scanned are just that, not an indication they are suspicious/infected, just unable to be scanned.
As Tech said a few common examples would help.