Open IE8 (you must use IE) to about:blank and clear your history / cache.
Go to your page. If you've been infected, the second hit out through your trade script will go to some scam anti-virus download page.
To be extra sure, after clearing your cache, load your page by clicking on someone else's site, rather than typing it in or using a bookmark. Load another TGP that has you in the toplist, and then click to your site.
This affects sites using both ATX and Trade Expert (possibly TP too, but not sure). They are overwritting the o.cgi file to steal your traffic, and admin.cgi so they can edit the file integrity tool to cover their tracks.
