How could she sing the role for so long and only NOW have vocal problems? Simple. Some vocal problems can be cumulative. What you thought was just a tickle in your throat can become a reoccuring sore throat... and snowball from there until you find yourself with nodes or worse. I've seen several very promising singers blow themselves out with bad technique or simply not warming up/maintaining the instrument correctly.
I'm not going to dip in to the "fired" controversy since it's mainly fan speculation at this point anyway. If indeed her voice has been damaged, I hope she rests it and heals up soon.

I don't care who you are- losing your voice can be a scary and traumatic thing.
*~* Every time you double-post, God kills a kitten. *~*
Kay, the Thread-Jacking Jedi
Quando omni flunkus moritati (When all else fails, play dead...)
"... chasin' the music. Trying to get home."
Peter Gregus: "Where are my house right ladies?!"
(love you, girls! - 6/13/06)