AlexxWoods, I read it off somewhere that she didn't want to be stuck doing tv shows forever. Or something like, only more elegantly phrased :lol: I'm sure you could find the interview if you look it off the internet.
I suspect the truth is that when Vanessa was offered the role of Aiden (she claimed she was the second person to be cast for the show after Gary Sinise), she thought it was a great opportunity to get exposed. Eventually, Vanessa simply felt it was time to move on to other projects closer to her own interests. She did say she might come back if Anthony Zuiker, the producer, asked, though.