[Typo3] Internal Server Error on BE extension

[Rick Gosselt]

Check you're server error logs.

If you have a premature end of script error the reason for this error is 
probably a rights issue.

Try lowering the rights of the extension directories. It's standard 0775 
believe. Try making it 0750.

Note: if this is a solution change the standard directory and file rights 
settings in the install tool to the right value.