Panel items duplicate on each reboot

[Mechphisto]

Using Mint 18 with MATE, and all of a sudden starting last night (after about 3 weeks of using this install), all the panel objects of been duplicating themselves when I restart the machine.
Two "Menu" buttons, two file browser icons side by side, two terminal icons, two time/dates, etc. Everything. Not two bars, like I see people having problems with when I google the issue, but everything on the one bar duplicated next to each other.

Fortunately I only have to do:

Code: Select all

mate-panel --reset

to fix the problem... (although if I want to put anything on the panel that gets rid of it).

So, I at least have a fix every time it happens... but, I'd love for it to stop happening every time! Any ideas?
Thanks!
L