Once in a while, the only keys that work on my keyboard are the keys that don't type letters (ctrl, shift, function, backspace) and it will stay like that until I turn the computer off and turn it back on later. Nothing warns me; I am just typing or playing games and then suddenly the keys that type characters stop working. (includes letters, numbers, and the other character keys like bracket, comma, colon, etc.) HELP THIS HAPPENS WITHIN TWENTY MINUTES OF USING MY COMPUTER