I can't imagine the keyboard having to do something with the GPU. What could be happening is that when you plug in your KB, you are jostling the backplate a little bit, causing something in the GPU to get loose, making it not respond. When you unplug it, it might do something that makes it move back into place. It would be pretty odd if it did this constantly, so it could also be the KB interfering with the GPU drivers or something, in which I couldn't help you.