Playing with keyboard and mouise. Also have a flight stick and throttle plugged in but I quitted the game, unplugged them and reproduced the symptoms.

Symptom:
Any scroll bar, horizontal or vertical, that has the yellow wolf paw cursor can at random have that cursor turn red and start moving randomlly as if it was possessed.

Workraround:
Clicking on a neutral area can usally un-focus the control but it's not guaranteed and often starts up again.

Impact:
It's annoying enough to make me swear at the screen.