Every once in a while, my numerical keypad only works as a mouse on my Ubuntu. I'm experiencing this behavior since the Intrepid version (8.10). Luckily for me it's not a big deal to solve it, but I had to google it every time. So perhaps by writing this small blog, it stays in my mind.
So to get the numerical keypad working again, go to System > Preferences > Keyboard
Then go to the tab Mouse Keys and clear the option "Pointer can be controlled using the keypad".
I still need to figure out which update causes this behavior...
My thanks to the person of this solution (http://bit.ly/47sAQ).