[TYPO3] .htaccess-protected frontend

[Felix Natter]

hi,

while developing a website I protected the frontend with a .htaccess file (HTTP
basic auth). Now when I remove the protection, I get an "Internal Server Error"
when trying to load the backend login page. The error disappears as soon as I
reenable the protection. There is nothing related in the vhost error log.

I already emptied all typo3 caches. What else could I try?

thanks,

-- 
Felix Natter