[TYPO3] Problems loading the ext manager in 4.0

[Thomas Rune Korsgaard]

Hello list

I've just set up the new 4.0 package in order to try it out. I seem to have
a problem the extention manager. I wont load. In IE i get a "page can not be
shown" and in firefox i can download the index.php file for the ext manager.
The problem can be seen here:

http://www.student.dtu.dk/~s011564/ext_load.png
(browser language is in danish, bu tyou get the idea)

I have a few other TYPO3 websites that run older versions, that dont have
the problem. The server it is running on is redhad 9, php 4.2.2, apache 2.0

Does anyone have an idea to what could be wrong?

Thanks
/Thomas