Shoutbox

I have this same problem on my laptop. I have a usb keyboard plugged in because i prefer the fullsize keyboard and if i happen to have "Num Lock" on on the usb keyboard and then type with the proper laptop one this exact same thing will happen. If i look on the keys you can see that there is numbers written in the bottom corner that is infact the laptop numpad.
Would this be the case with you? i know it sounds pretty simple but that is like the exact problem i have if i have num lock on.

i always have num lock disabled, so no i don't think it is the same