[TYPO3-english] $GLOBALS['TSFE']->fe_user->user['uid'] is empty

[Jeppe Donslund]

After fe user login $GLOBALS['TSFE']->fe_user->user['uid'] is empty.
How can that be?
It worked yesterday and I can't imagine what has een changed.

It is TYPO3 4.2.8.

Regards
Jeppe Donslund