I've got a bug when I've clicked on the link for incrementing +1, +10 or decrementing the chapter -5.
I'm using FF4 and i've got no errors in Javascript Error Console. Nevertheless, it works fine on IE9. So I actually have to switch between the 2 browsers.

Clear your cache.

We should probably put this in the FAQs since this question keeps popping up...then again, no one reads the FAQs section...