Here's a weird one...
I installed the Sociable Facebook Connect plugin. It went all screwy on me and messed up my dashboard page. I thought it was a hack, but it turns out it was just a plugin problem stemming from attaching a new Facebook application API to my WP account.
The problem of a totally separate user name designated to my account now exists. And I don't know how to get rid of it.
Any help in deleting this user name and its connection to my account is appreciated. It's basically a "FB_" username that attached a totally random FB proxy email to my account.