I though you would have known about this already - Please ‘modify’ your post change the URL from http to hXXp or www to wXw, to break the link and avoid accidental exposure to suspect sites, thanks.
The process no doubt is as a result of the web shield rerouting the request from your browser to visit that site. So were you trying to connect to this site ?
Do you use Chrome and do you have this Niederschlagsradar extension for Google Chrome (With Niederschlagsradar users can see the German weather forecast.) ?
Use the on-line contact form, to ask for a review 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 field open, click Browse button and navigate to the file or enter the web URL for the site you wish to submit for review (network shield possible false positive), etc.