Sorry for the late reply. This is usually a single-account computer, as nobody uses it but me.

For the sake of testing, I went ahead and made a new account ("Test"), and the bug does -not- occur...

That is probably a different issue. The one mentioned in this thread only affects one taskbar entry.

Registered to say I have the same problem and to give as much detail as possible.

In case anyone has a problem understanding the OP's description of the issue, it's fairly simple:

Right-click...