Stuck on login screen, can't select a user
I have at least partial success booting in safe mode but have experienced similar behavior. But I found that if I went away long enough, the condition cleared and I was eventually able to log in.
(Prior to this, I was having trouble re-establishing TimeMachine backups after having not run the regularly for quite awhile.)
Help would be greatly appreciated!
Mini, Mac OS X (10.6.6), 4 GB RAM