hmmmm... Once you log on you simply go to the forums. Are you sure your password is correct? It may not be being very clear about it being incorrect. The only thing I can thing of based on your desc. (Might be a javascript thing going on with the browser.) The site is php so shouldn't be an issue there with the browser. Check to make sure you don't have a javascript blocker on or another isse.

No need to think outside the box....
    Just make it invisible.