Rod,

Avast does use a bit more resources due to the manner in which the scanner uses its’ engine. It is negligible.

Avast will use more when set for a Thorough scan including Archives.

In the future, a different method may be used, but the present is the best compromise for now.

As for the “unable to scan” entries. You will find that some of the files are Password protected. These are usually system files that Window protects to avoid tampering.

Other files may be “in use” and are “locked”.

Still others may be in the System Restore.

If you use Adaware and put any files into Quarantine, they will also show as being “unable to scan”. Just go back into Adaware and clean out the Quarantine folder.

In order for me to tell you exactly the reason, I would need to see the scan results.

BUT…it will be one of the reasons I just gave you.

Thanks for asking, and welcome to the forum.