Multisite wordpress 3.0.1 behind a apache proxy

i’m running 5 worpress instances sucessfully behind a apache server using rewrite rules for some years now.

now i thought it’s a good idea to give the mulitsite feature in wordpress 3 a try as it would ease the support of these websites. my problem is:
– i installed a new wordpress in the root of my internal server
– i configured the external apache to do the redirects to the internal server
– i configured the wordpress successfully, whith the litte glitch that i had to edit the site URL and blog URL to the URL of the external apache
– everything worked with no problems
– i enabled the multisite feature in wp-config.php
– i completed the network setup with the url myserver.com (without the www) and copy pasted the code to wp-config.php and .htaccess

now i’m in trouble because i get the infinite redirect loop and can’t access either the blog nor the login page nor the admin interface. i retried the whole setup with the url http://www.myserver.com but no difference.

now my question:
does anyone has a similar setup up and running? do i have to hack something to get this to work? can anyone tell me what’s wrong?

regards, wolfgang