BuddyPress.org

@irishartisans – I’ve never known anyone use rewrite.script. Mod_rewrite.c is the norm for WP / BP

I suggest going back to the original .htaccess file, then de-activate BuddyPress, and then run the following tests:

Do custom permalinks work (e.g. change them to /%category%/%postname%/ in your wp-admin), can you comment, can you register new sites, and so on.

Does all this work without problem? If not, check you have correct permissions set on your .htaccess file