[ubuntu] Firefox won't start after update

Hi,

Firefox tried to update itself, but now it does not seem to start again. When I click the icon in the launcher, it flashes (as if it is about to start), but then nothing happens. I caot run it with sudo. I'm still ruing Ubuntu 11.04, though - I don't know if this has anything to do with it.

Can anyone help, or offer ideas?

Thanks