Donno but I think google is seeing some problem in linking. ..
http://www.translatum.gr/forum/index.php?PHPSESSID=7d3725a1b32241c40c4bd57a7bd4e74c&topic=14883.0 You are using search engine friendly URL of SMF but google is getting simple URL...
.. so .. find out how it is getting those URL .. is it something with search engine.. see Google webmaster tool and verify if google bot is seeing right URLS.