Taskbar Crashing - Disappears For A Second And Then Restarts?

Recently, my taskbar started doing a strange crashing/restarting thing. It disappears for a second, leaving behind the drop shadow, then restarts and works fine. Looks like this:

See the shadow line there?

I was able to duplicate it when I realized it would happen each time I opened an old program, but also happens at seemingly random times. Sometimes it takes just a second to reboot, other times it stays this way for a minute before returning.