does a code signing certificate help with false positive from a virus scanner
We purchased a code-signing certificate and we still got flagged by Symantec so it's no guarantee. In the end we contacted their white-listing service and they eventually got back to us to say our app had checked out and it would be whitelisted. Never had to deal with AVG so can't comment on their process (or lack of).
Intuitively, I'd say no. If signing your code was all it took to get past antivirus software, then a few hundred bucks would be enough to make all antivirus software completely useless. A code signing certificate certifies that the code comes from you, not that it is not malicious.