Bob,
This is very odd and I don't what might fix it. I assume you have run a permissions check. If not you should try that. You should probably look into using Onyx or some similar utility to verify that you system is working to snuff. If all that checks out, then you might consider reinstallation of programs (bleah!). However, since this occurred after installing an update it seems likely that something happened during the update. Since we are not hearing of a lot of issues from others here (I haven't looked elsewhere) it does not seem to be an incompatibility issue.
As a general good practice (not that I practice it
) it is ideal to get a good back up just before installing an upgrade. That way you can always go back to just before the upgrade and keep going.
Good luck.
Erich
AC 19 6006 & AC 20
Mac OS 10.11.5
15" Retina MacBook Pro 2.6
27" iMac Retina 5K