[TYPO3-english] Error after changing the baseUrl

[Jeppe Donslund]

I have a site which af been placed on a subdomain while setting it up.
Every thing works fine.
When changing the baseUrl somthing strange happens.
Using a login form the user are forwarded to the right page but 
$GLOBALS['TSFE']->fe_user->user is empty.

How can that be? I have searched forums and mailinglists without finding 
anything else than that it could be related to cookies with wrong urls.

Regards
Jeppe D.