BuddyPress.org

What OS are you running locally, and what browser? I’ve installed the trunk versions of both WPMU and BuddyPress on two local installs so far, and haven’t experienced these issues.

When you say that directories.css wasn’t being loaded, was it 404’ing or was it just not mentioned at all?

I’m not on my laptop at the moment so I can’t see where directories.css is included normally.

When you updated, did you DELETE your old files and upload your new ones? Delete browser cache, site cookies, etc…