I recently upgraded to Firefox 2.0. Nice changes all around — but when I went to Voo2do, my usual Alt+S key press to save tasks simply didn’t work. According to this blog post, this is because Firefox 2.0 has changed the access key combination from Alt to Alt+Shift.
So try Alt+Shift+S to save tasks and Alt+Shift+K to add a new task. This is a confusing change and many web users will be affected by it.