Hehe, yeah, definatley not the first. I was writing something once and not looking at the screen for a bit and when I looked up, I was shocked to see half my words were speckled with numbers.
Turns out I had the FN lock on and the numeric keypad on my laptop was activated. Ooops.
I thought my keyboard was shorted out or broken.. I even rebooted.
Few minutes later it dawned on me.