Hi and welcome

This topic is covered in the following thread.

http://forum.avast.com/index.php?board=2;action=display;threadid=4764

Hopefully this should be help.

There is a large amount if information on the forums and it is all available to you using the search button at the top of each page.

A search on false positive returned 20 posts (including this one)

Hopefully you will only ever have to worry about false positives