- What avast! version and VPS file (virus database) number, e.g. 0436-4 (see about avast!)
- What was the virus name, what was the filename, where was it found
example (C:\windows\system32\infected-filename.xxx)?
From the information above, e.g. the file name detected you should be able to have a detailed exclusion, you also need the exclusion added to the resident scanner Standard Shield, Customize, Advanced and not just the Program Settings, Exclusions.
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 new, undetected virus or 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), when it is no longer detected then remove it from the exclusions.
Also see
(Mini Sticky) False Positives