After using Update Manager to upgrade to Jaunty, Ubuntu will not boot

[LobbyDizzle]

I get to the log-in screen, but once I enter my user name and password, it goes to the Ubuntu-tan screen and just sits there. The only thing I can get to pop us is the screen selector dialog using Ctrl+Alt+< or > arrows.

[LobbyDizzle]

Let me be more specific. I gets to the screen where the intro music would normally play, but it never does.