Admin page in 6.1 - 500 Internal Server Error

I installed Dolphin exactly as it says in the install instructions. The website is working just fine, the groups, the events, the classifieds, orca, all but the admin section. When I try to access the admin section (http://www.motobox.ro/admin) I am getting this error :

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@motobox.ro and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

 

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

This is not my first Dolphin installation. I am running another website based on Dolphin that is running perfectly. I tried to remove from .htaccess file the line php_flag register_globals Off and the error still persists. I have no clue on how to solve this problem. I checked and mod_rewrite is enabled on my server. Can someone please point me in the right direction in solving this error.

The URL is : www.motobox.ro