Unfortunately, it could be anything on the page causing that message. The page has a lot of individual scripts that make it work. For example, the "forum jump" menu that lets you move from one forum to another is a script, and the thread tools that lets you subscribe to a thread is a script. The message you received is very generic, so it's impossible to pin it down. If stopping the script lets you use the forum normally, then whatever was loading must not be necessary
I don't think it's anything bad, or your antivirus would alert you with a more specific message.
I hope that helps