How to unstick the stuck Control key on Windows

Sometimes on my Windows 7 out of the blue the control key becomes stuck, that is the computer behaves like the control key was pressed all the time. It is really annoying, but there is a simple trick to cure it. Just press the control, alt and shift keys on the left side of keyboard, one after the other, then press these keys on the right side one after the other. This usually solves the problem for me.