I'm using Donncha's domain mapping plugin, and it was working fine until I changed the name of one of my two mapped blogs. Now I can't access the backend for either blog unless I not only deactivate the domain but delete it altogether. The backend url redirects to the front page of each blog. When I reinstall the plugin, the problem reappears.
These are the two blogs:
http://wpyogi.com
Backend url: http://wpyogi.bornfamous.com/wp-admin
http://healthbuzz.org
Backend url: http://healthbuzz.bornfamous.com/wp-admin