Resetting the Windows Registry User Keys as described on this website is what finally did the trick:
Here are the critical steps described in the link:
These registry keys store user application settings saved between ArcGIS sessions. This includes some application options, default folders used by open dialogs, certain screen window positions, and other settings.
A common reason to reset your registry is if your window locations are kerfuzzled from working with multiple monitors and you want to return them to defaults.
Since DOI/USGS security settings do not allow users to run the regedit utility to modify HKEY_CURRENT_USER, you must get to these settings using the Windows command line.
Close ArcGIS desktop applications.
This is important! You may want to check Task manager or log out and log in again just to make sure no headless ArcMap processes are running.
Open a command window (-R, type "cmd" in the box, )
At the command prompt, enter:
reg copy HKCU\Software\ESRI HKCU\SOFTWARE\ESRIold /s
reg delete HKCU\Software\ESRI
Log out and log in.
When you next start an ArcGIS application, new HKCU\Software\ESRI registry keys will be created and populated.