UBB.threads PHP Forum Software Community Forums UBB.threads 7 Bug Reports Help...Redirect Bug or malicious code?

I am using UBB.threads™ 7.5.3 and need help with what may be a bug or some malicious code.

The site is randomly redirecting to http://stonecliff5.com/stop.php sometimes when you click on the breadcrumb "forum" and also when you are viewing pages.

It is sporadic. I checked all the third party ads I run on the site and there is nothing. I contacted them and they have no advertisers that run this website.

I did a Google search and there is only 2 references to this site. One is a discussion on it being a bug and the other is a PHP answers page that does not have any reference to the URL.

Here is a screen shot of - http://jamaicanewsletterservice.com/images/errors/cliff5_error.jpg

what is your forum URL?

Is it happening to just you or to others on your site as well? If it's just you, then it could be some type of virus. If it's happening to multiple people on your forums, then I'd say someone might have some malicious code that's causing it, and you'd probably want to look through your site for any recently modified files that you haven't actually changed.

Here is the Forum . It is happening to other users. See this thread.