When I start my computer, everything is fine. As long as I continuously use it, I have no problems. If the computer ever goes to sleep, however, I can use the mouse or keyboard to wake it up, but I cannot actually use anything. Even CTRL-ALT-DELETE doesn't work. If I boot my PC into Linux, I don't encounter the problem.
I have run a Virus Scan and Malware scan and found nothing.
What I have had to do recently is to hold my power button down until the computer shuts off, then power it up again.