[Typo3] Error: The main frontend extension 'cms' was not loaded.

[Søren Ulrik]

Hi

I have serious problems with one of our sites. After restarting mysqld 
(due to errors), I got some errors in the frontend, so I cleared all 
cache from the backend. After that I only get

"Error: The main frontend extension 'cms' was not loaded. Enable it in 
the extension manager in the backend." in the frontend, and in the 
backend, all modules have disappeared. The icons are appearing in the 
left menu, but the links have disappeared, so there is noting I can do.

  When I compare with a running site, the extension cms is not mentioned 
in the extension list in localconf.php.

I really bad need a hint on how to fix the problems!

/Søren Ulrik
Aalborg, Denmark