Hi,

Probably a rhetorical question : have you checked Windows Settings => Taskbar  ?

If that's not it, you could try this : https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

If that doesn't work either, let's try Firefox in Safe Mode :

If Firefox is not running : Hold down the Shift key when starting Firefox. If Firefox is running : 3-bar menu => ' ? ' (at the bottom of the dropdown) => 'Restart with Add-ons disabled'. Then OK the restart. A small dialog should appear. Click 'Start in Safe Mode' ( not 'Refresh' )

See : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Try to rename/remove xulstore.json in the Firefox profile folder with Firefox closed.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

First, there was nothing in the task settings pertaining to full screen or otherwise.

Second, my issue seems to have resolved itself. Last night it was having a problem. Tonight? No problem. Technology sometimes, ugh

MasterofBalance said

First, there was nothing in the task settings pertaining to full screen or otherwise.

Irrelevant now, but it definately should be  !

Second, my issue seems to have resolved itself. Last night it was having a problem. Tonight? No problem. Technology sometimes, ugh

As my answer did not solve your problem : would you be a dear and remove the Chosen Solution mark from my post  ? You can do so by clicking the 'Undo' button to the right of that post and then mark your own (last) post as the one that solved your problem.

I'm glad everything is back to normal - whatever happened : let the mystery be .....