Visitors of my forum report malware and porn popups

Hi

i got a message from several visitors of my forum that my forum contains malware. Someone wrote me following:

http://reasonandscience.heavenforum.org/

I have been viewing your materials and although long, they are good. But when I click links to your site, I get pop ups, including one that was pornographic in nature and also one that highjacked my browser while on your page, purporting to be from Microsoft, saying I have the Zeus virus and telling me to call a certain number. I have run several scans and followed the removal instructions, but none of the trojan files show up. This may be because I have been running the computer on safe mode with networking for several weeks. So far, I only experience the problem when I go to your site, so I think it has been compromised and that my own unit has been protected by operating in safe mode.

i ask the forum support team to solve the problem.

thanks