Do you have a "num lock" key that is activated on your keyboard?
On a laptop there often are small numbers on the keys M=0, J=1, K=2, L=3, U=4, I=5, O=6 and so on.
When the num lock key is not active, you type the numbers on these keys by holding down the fn key. (As a replacement for the number keys to the right on a big standard keyboard.)
If the num lock is active on my laptop (Mac PowerBook), I'm only able to type the numbers on these keys. The other keys on the board are "locked".
But it you've got a PC, I guess the num lock key may lock only the number keys to the numbers.
kifoy