[TYPO3] Broken links in backend

[Lukas]

I have a typo3 installation (3.7) that have been up for more than one 
year. But not I suddenly got broken links in the backend. When I click 
on "page", "template", "list" etc in the left frame, I get a 404 page 
instead of the real stuff.
The main frame url is 
http://www.my_server.com/typo3/alt_mod_frameset.php?fW=245&nav=/typo3/mod%2Fweb%2F..%2F..%2Falt_db_navframe.php%3F&script=..%2Ftypo3conf%2Fext%2Ftemplavoila%2Fmod1%2Findex.php&id=