I never have this problem before. W7 was working just fine for almost 4 months. I didn't install or plugin anything new. I was typing something and then my "W" and "A" buttons don't work". So I restart my computer and then BSOD came up. I reboot my computer and type something then "I" button doesn't work. I reboot my computer again BSOD came up again. Now I can type just fine but I don't understand what happen. I didn't install any thing new. Thank you.