I have 4 monitors and a taskbar on each. Each taskbar has a set of program icons but from time to time, I notice that one of the pinned ones dissapears. It leaves a blank space where it was but, it is gone.

If I go to Programs and right click the program to pin it again, it gives me the option to Unpin the program so, Windows and DF still thinks it is pinned.

What's happening here?

Thanks