Joomla 3.1 site throws 404 when SEF and re-write is set on

Joomla 3.1 site throws 404 when SEF and re-write is set on

I have two developing sites in their own folders on the same Apache server
- both running the same version Joomla and using identical php.ini,
htaccess, and index.php files
One works perfectly when URL re-writes are turned on -
http://media2learn.org/kca
The other (only difference is it was migrated from a Wordpress site using
CMS2CMS) gives a 404 error when URL re-writes are turned on. It works fine
with only SEF on.
Do you have any suggestions - I have no idea where to go from here. The
site with re-write on: http://media2learn.org/starhavenkennel