BuddyPress Support Plugin 1.0-RC1
If you are truly using BuddyPress 1.0-RC1, then that is your issue. There have been many bugs fixes and improvements since RC1. It’s time to upgrade to the 1.0 public release and try the process again.
Since RC2, BuddyPress is a single plugin that resides in /wp-content/plugins/. Make sure you follow these revised Installation procedures very carefully.