[TYPO3-install] New Typo 6.1 -> You are not allowed to access the given folder

[Matthias Friedrich]

Hy all, 

im new at Typo3 and on my first installation i have some issues, maybe some one can help me to solve it.

I downloaded the latest version and call the index.php for the install process, all fine, i see a demo page and i can log in to my admin account!
Also here works the most, i can add pages, change content and so on.

But when i try to access the "Language" section i got the message "You are not allowed to access the given folder"
But im logged in with the admin account...

i have already tried -> php 5.3, php 5.4 and php 5.5, all with enabled / disabled apc cache and memcached

Some ideas ?! Im lost :/

Thank you all !
Regards
Matthias