Hi and welcome,
I don't recall seeing this mentioned as a problem before, so with one exception I'm sorry I can't offer suggestions.
For a start, though, try updating the program -- current version is 4.1.357 as of about a week ago. Among other improvements there were some bug fixes, although as I said I don't remember hearing of your problem before.
There'll be more experienced help along before long, and hopefully they can offer useful suggestions whether or not the problem's related to avast, which I don't believe it is.
Best,
Mike