Touchpad scroll feature sticking

Most times when I put an Internet video (such as, but not limited to, YouTube) in fullscreen mode, it makes my touchpad (silkscreen) scroll feature unresponsive.  Sometimes it fixes itself, but usually I have to restart my system.  Nothing else seems to fix it.  Any ideas?

My touchpad is made by Synaptics.  I have thought about updating driver for it, but I have had no other problems with it, so that does not seem like the problem.