I've had my desktop for a few years and never had a problem. Just recently, it has started showing a Keyboard Error message on a black screen when I boot it up. The wireless keyboard and mouse do not work, although it appears to boot up correctly. Since I have a password on my computer, I cannot log in or do anything. When this happens, I've rebooted 2-3 times, and it the keyboard and mouse will finally start working. I have moved the toggle to different USB ports and this does not appear to make a difference. How do I prevent this from happening?