Hello: This is my first post. I keep getting the above message when I scan, or at the end of a complete scan, I should say. I have no idea what it means or how I can remedy the situation. All I know is that there are a ton of files that are not getting scanned. If anyone can help explain this to me, I’d really appreciate it. Thanks much. Mike D. Oh, I have the 4 Professional Edition.
See http://forum.avast.com/index.php?topic=35347.msg297170#msg297170 this topic for more information on why files can’t be scanned.
Files that can’t be scanned are just that, not an indication they are suspicious/infected, just unable to be scanned.
Thank you, David R. I appreciate your timely and thorough answer. My best wishes to you.
Mike D. (schbibby) 
No problem, glad I could help.
If there are still some you are unsure of post some common examples, giving the file name, location and reason avast couldn’t scan.
Welcome to the forums.