This tool has been discussed many times already. Please use the Search feature before posting new questions.
Here’s some of the relevant threads:
http://forum.avast.com/index.php?board=2;action=display;threadid=4979;start=msg36041#msg36041 http://forum.avast.com/index.php?board=2%3Baction=display%3Bthreadid=778%3B
Thanks vlk