Per the screenshot below, I can no longer navigate through my folder tree when clicking the arrow at the top of a file list. This issue occurs in Windows Explorer itself, and in Word 2016. I suspect it would occur in other apps too. (Please forgive the whitespace in the below per redacting...)
You'll also note it has an entry for CMD.EXE which seems bizarre.
The only change I can think of is that Dell did some work on my computer late last week.
Is there some setting I need to change?