Forum Facebook - when clicked reloads page and adds &dofbredirect=1 to the url
 

if I click on the facebook button to login ...
nothing happens except the url gets :&dofbredirect=1 added to it like

http://www.mysite.com/?dofbredirect=1&dofbredirect=1

any ideas what could cause it ...
the only thing I did that seemed strange to me is because I dont use the cms as the homepage I coppied forum.php to index.php .... would that cause this issue?