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 @ avast.com (no spaces), or send from the chest.
Give a brief outline of the problem (possibly a link to this thread), the fact that you believe it to be a either 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.
If it is indeed a false positive, add it to the exclusions lists (Standard Shield, Customize, Advanced and Program Settings, Exclusions) and check scan it periodically using the ashQuick scan (right click scan, it will need to be temporarily removed from the standard shield exclusions otherwise it won't be scanned), when it is no longer detected then you can also remove it from the program settings, exclusions.
Also see
(Mini Sticky) False Positives