Why can't you scan certain files?

I recently had this program installed, after viruses had wrought havoc on my MacBook Pro.

I am STILL having problems with a virus; yet Avast REFUSES to scan certain files: precisely the ones in which this bug is obviously hiding.

Why can’t you DETAIL the files you’re ‘unable to scan’, and at least tell me WHY you can’t scan them???

For Heaven’s sake, why don’t you make it so that you CAN scan the damn files and get rid of the virus? >:(

1]
This forum is for avast for windows.
The Mac forum can be found here:
https://forum.avast.com/index.php?board=5.0

2]
avast already has told why certain files can’t be scanned:
https://blog.avast.com/2014/02/28/how-do-i-handle-files-that-avast-cant-scan/