I know, big surprise - we're having trouble with an IIS install of WPMU (v1.2.4) on a Windows 2003 server with PHP & MySQL. We also installed "IIS Mod-Rewrite Pro" which seems to be working great:
http://www.micronovae.com/ModRewrite/articles/CleanPermalinks.html
Right now we have the main WordPress MU installed with 1 additional sub-blog. From a users perspective, the site works correctly, meaning when you go to the main blog or the sub-blog you see the the appropriate posts.
But when you login to the admin panel, you can only edit the main blog. When you switch to the sub-blog the url in the browser location bar changes to display the sub-blog url - but the admin display still shows the posts for the main blog.
We also tried setting up a separate user for the sub-blog, but then we are not able to login at all. Trying to login creates an endless redirect loop (between the main blog login url and the sub-blog login url) and Firefox gives the infamous error message:
"The page isn't redirecting properly. Firefox has detected that the server is redirecting the request for this address in a way that will never complete."
Of course the identical files loaded onto a Linux box work perfectly, but unfortunately we are being forced to use the IIS platform.
We have spent several days trying to find potential solutions to this problem (here and around the net) with no luck. If anyone has any suggestions they would be greatly appreciated.