First, let me say I have been reading the other threads... and have come close to solving this.
Second, thank you to everyone for their help.
Third, I had a working WPMU site that I did upgrade okay to wp3.0. Then in the process of adding some code to the config file, I killed the connection. I couldn't get it back.
So, I decided to start afresh. I replaced the code in the rood directory with a brand new version of wp3.0.1. I made a new database. I began the set up. (yet again.)
Ok... one thing I have learned is that you should set the pretty permalinks first.
Now... the buddy press works. the network is set up.
Two things are happening:
No CSS on the Sites
No dashboard for the sites.