BuddyPress.org

Try this:

1. Fire up phpMyAdmin
2. Go to the appropriate DB for your WPMU install
3. Navigate to the wp-site table
4. Click the “Browse” tab. You’ll see the data in that table
5. The first record should be for your website’s domain with the path to your WPMu install
6. If that is different than what it should be, make the change there, save, and close.

Of course, as always, back up your database before making any changes to your data directly or changes that could affect the accessing of your data.