Buddypress on Nginx loops in 302 redirect

I'm having problems with my test site - I would like to add BuddyPress plugin, but when I do, I get "To many redirects" error.
It seems that site is in a redirect loop between index and register page ( BuddyPress registration page ).
When I disable buddypress everything is ok.
If I disable everything but buddypress error is back again.
I've asked on Buddypress forums but no reply there.
I've searched the internet and no luck there also.
I have went through all tutorials on Buddypress and Nginx and can't figure out what is happening.