From the program's [Help] file:
Info and Service :: Report false positive
If you believe that Avira AntiVir Personal reports something about a file that is most likely "clean", send the required file packed (WinZIP, PKZip, Arj etc.) in the attachment of an email to virus@avira.com. As some email gateways work with anti-virus software, you should also provide the file(s) with a password (please remember to tell us the password).