They are indeed exclusions. However they are not optional exclusions. Is there no way to force Avast! Pro 4.8 check these files while in the operating environment or at least in a BTS? I took a look at Avast! 5 and apparently it does have exclusion options that will allow one to scan them. Unfortunately 5 is, or at least was, relatively unstable.
It is not unstable…!! Which system are you on?
Maybe you should try the 5.0.545 version…??
asyn
Could it be you left/lost your thread (in V&W) somehow…?? 
asyn