So why no posts for Windows 10? I believe Avast may be causing a lag viewing video's on Facebook. No problems with my windows. All up to date and my Desktop is less than a year old.
The fact that the can't be scanned means only that, they can't be scanned and avast is reporting that fact. If you had searched on file can't be scanned, you would most likely find a huge number of posts as this is a very common question.
Here is one almost as old as this topic and the reason hasn't changed. 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.Many programs (usually security based ones) password protect their files for legitimate reasons, there are others (and avast doesn't know the password or have any way of using it even if it did know it).
By examining 1) the file name, 2) reason given by avast! for not being able to scan the files, 3) 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.
If you can give some examples of those file names, the locations and reason given why it can't be scanned might help us further ?