[greenyoda]

"someone decided to flag the installer"

This most probably wasn't a malicious action by a competitor. Anti-virus programs frequently report false positives - they're far from perfect.

Installers tend to do weird things that are similar to things that viruses do, e.g., write to the Windows registry. Maybe your installer is doing something in a way that made Norton think it's malicious. The fact that Symantec has a simple process for dealing with situations like this would be an indication that they frequently make mistakes.