My TF-300 and dock has worked fine for almost 2 years. Today I find the keyboard on the dock is not working any more. The backspace key works, but when I hit a letter key nothing happens! The TF-300 reconizes the dock and shows it is connected and charged, but I have to remove the tablet from the dock and then use it's on screen keybaord to type anything. Anyone have any idea of how to fix this?