If something like that happens, then there usually is a key stuck... to stop them from running in a circle, or un-stuck the keys, simply go to that toon's client and press one or even two of those stuck keys... that should solve it..
My problem usually is a stuck modifier, like Shift, CTRL or ALT... I simply hit all of them one after another, what solves it for a while, until something weird happens again (has to be something weird to get them suck, cuz my accessibilty options for locking keys are off)
I could imagine, that this might happen, if you activate a window, press a key and while the key is pressed, the window loses focus again..