Although this appears to nave nothing to do with .NET, I had a similar
experience with Avast when building a couple of new Win 7 PC's and
installing Avast from a previously downloaded install package.
It was solved when I forced an online update to the latest available
subversion of Avast. Note that the automatic update facility provided by
Avast was *not* fixing the issue. So, go to the Cyberdender web site, or use
the manual update facility to get the latest version.