WordPress MU

Hello, excuse me for my english, I'm french.
I have a big problem. I can't access to the admin of the principal blog of WordPress MU. I change the password but the problem it's the same.
I contact the support of my hoster, they tell me that it's a bug of WordPress MU!
I can enter in the admin of all children blogs but not the principal blog.

Have you met this problem ?
I need help
Thanks you very much.

Might help us help you if you told us exactly what is occuring. "I can't access to the admin" gives us nothing to go on I'm afraid. Are you seeing an error? Blank screen? Images of Nicolas Sarkozy singing Klingon Opera? ;)

Hi,
There's no images of Images of Nicolas Sarkozy singing Klingon Opera?

I have this message in french in Firefox:

Redirection de page incorrecte (False page redirection)
Firefox a détecté que le serveur redirige la demande pour cette adresse d'une manière qui n'aboutira pas.

And in Internet Explorer, the page didn't change , it left in the page login.php indefinitly!!!

Thanks