Num Lock is on for boot, Win login etc but keeps turning itself off... G9-793

OK, I'm having issues with the Num Lock turning itself off. It's on for boot, on when entering my code for Windows login but then it'll eventually turn itself off without the button being pressed. I turn it on again and within half an hour or so it's off again and it's annoying as all hell. The lack of an LED indicator makes it even more infuriating. Does anyone know what's causing this or have a way to make it stay on all the time? Oh, and for clarification, if the screen locks after being idle for a while and I then have to re-enter my windows login the numbers will work without me having to hit NL, but then mere seconds later when back to the unlocked desktop the NL is again off and I have to hit it again manually!!! ARGH!!!!