This site has always been clean for me.

Chances are your PC was already infected by something which was actively running or downloading while you visited this site. There is no active or executable code (let alone any malicious code) on these forum pages - aside from the usual (and, on these forums, very limited) browser, java, flash, plugins, etc which run on your client, not on the web server.

It is, however, possible that your antivirus identified files on your computer which came from this site but have been altered/infected by whatever's already infested your machine. Install (and/or update) your firewall, antivirus, and antimalware software from clean copies (downloaded on a clean and secure machine, from the official source sites, onto a removable drive, if possible). And run a full overkill comprehensive scan overnight - if you've already found one infected file (which, I think I can promise, was originally a clean file at this site) then chances are multiple data objects on your computer have already been compromised. Problems of this sort tend to persist and tend to multiply if left unattended.

You might do well to uninstall all browser toolbars and add-ons, clear your caches, and reset everything to default settings. Or simply install a different browser. Microsoft IE is deeply embedded within Windows so it can do a lot of damage (notoriously through ActiveX, .NET, etc) to your OS and data which - in my opinion - a stupid web browser should never be able to directly access. Twice as true if Windows Updates are neglected, as they not only fix problems but openly announce which problems a hacker can exploit on unpatched systems. Chrome or FireFox are better, at least until too much dirty java and too many dubious add-ons get installed.

And if you're a gamer then you must resist the temptation to "temporarily" deactivate your security software in the interests of increasing performance. It's a bad habit which, one way or another, will eventually cause problems which wreck your data and waste a lot of time.