scanning

Ran a virus scan. Found seven virus’. Also many files in which was stated “Unable to Scan”. Why cannot it scan certain files? Can this leave a virus in the system?

Would appreciate some advise.

Also many files in which was stated "Unable to Scan". Why cannot it scan certain files?
It should say why in the message!..... anyway there can be many reasons why they can not be scanned, password protected zip.files, encrypted files, files that belongs to another security program and is protected by it........ files that can not be scanned, means only that and not that they are infected

OK Thanks for the response. I appreciate it very much