Most probably it's a false positive.
You can submit the file to
Jotti and let us know the results, i.e., if it is or not a false positive.
If you are getting a virus warning that you believe is a false positive, then if you can zip and password protect ('virus', will do) the suspect file and send it to virus (at) avast.com.
Give a brief outline of the problem, the fact that you believe it to be a false positive and include the password in the body of the email. Some info on the avast version and VPS number (see About avast: right click avast icon) will also help.