Hi Wolg,
I too have similar problem with my 5 year old HP laptop. It starts typing in the comma characters continuously whenever it boots up
(rarely when i'm doing something also). After lot of trials I have found that if I press the Esc key twice, it goes away. Then i cannot type the comma character after that (until i restart). I used to have a file in my desktop with the comma character typed in its name so that i can copy and paste it when im typing something.
Since this worked for me, i never did any further research on this. I'm closely following this thread to see if I can also find a fix for this.