EasyDiscuss Threads Being Hijacked by Malware

I am using EasyDiscuss Version: 3.2.9304 on my Joomla 2.5.27 website. Whenever somebody clicks on a particular thread/topic on my EasyDiscuss page, they see the topic they wanted for about 1-2 seconds before the page suddenly gets hijacked to an ad page. On the many thousands of pages my website has, this virus or malware hijacking only happens on the EasyDiscuss threads.

Clearly, my EasyDiscuss program has a virus of some sort. Any suggestions on how to get rid of it? Once that is done, any suggestions on how to keep it from ever coming back?