BuddyPress.org

chouf1, the bpc 1.0 alpha 2.1 version is only if you are running bp 1.0.1.

If you updated to bp 1.0.1 in the first few hours of it’s life, you should download and install it again. That initial release had some problems with certain sites and plugins. The problems were fixed and you should download and install bp 1.0.1 again.

The exact symptoms you are describing are what I ran into also with bp 1.0.1. Andy fixed a couple of things and updated the download. The changes were just slipstreamed. The version number wasn’t bumped.