Re: BuddyPress says themes are missing, but they aren't
It worked for me – and I suspect plenty of others – so there’s probably a bug lurking somewhere.
So just to check – delete /wp-content/bp-themes/. Put the new two theme directories into /wp-content/themes/. At this point, going to the BuddyPress admin backend (in /wp-admin/) will get you a red warning box.
Then go to http://example.com/wp-admin/wpmu-themes.php, activate ‘BuddyPress Default’ (not ‘BuddyPress Social Network Parent Theme’). Then you should be able to activate the ‘BuddyPress Default 1.1’ theme on http://example.com/wp-admin/themes.php.