Forums / Cotonti / Support / Page doesn't load - Tries to download the file

hey again ;) 

so we set up a test subdomain for our main page.. and used the same database all imported correctly.. config is set correctly too.. all the other files are identical to the ones in main site...

what we get when we click the link for e.g. google.com - enter - download window pop ups - trying to download "default" file? 

what is the problem? something set up wrong? any ideas?