There are heaps of websites that have this problem which relates to code inserted that redirects based on HTTP_REFERRER header. It doesn't happen in Bing or Yahoo for me so seems like it is only doing it on Google results.
In the network traffic the initiator to filestore72 is
www.fordforums.com.au/misc.php?v=387&js=js:1
So I'd start with looking at that file for code looking at the referrer headers. Something admins will have to do though.