Send the sample to avast as a possible False Positive:
Open the chest and right click on the file and select 'Submit to virus lab...' complete the form and submit, the file will be uploaded during the next update.
Or - There is a new on-line contact form,
http://www.avast.com/contact-form.php?loadStyles for: * Sales inquiries; Technical issues; Website issues; Report false virus alert in file; Report false virus alert on website; Press (Media), issues.
- If you are reporting an FP, then you get another input filed open, click Browse button and navigate to the file you wish to submit.