Gary,

While you (and MotoX80) are thinking, I should mention what other related issue I found (and corrected?) on this particular W7 laptop, B/V3500.

At one point the admin shares C$, D$, etc. were not showing up locally ("net share"). What I found is a registry key that prevented it:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters with AutoShareServer and AutoShareWks with values of "0". (https://support.microsoft.com/en-us/topic/c73f5ae7-84b7-982b-db63-e23ade47efe7)

Using the registry ed. (with fear and trembling) I changed the values to "1".  Now they show up... Perhaps I should have deleted them. (BTW, the W7 comp "C" (Karen-PC) that "works" does not have these entries.)

Rest assured that I did not edit the registry to make this change. I wonder though whether maint.  s/w (like Advanced Sys Care) suggested a change I went for - perhaps it did other things. I would not have noticed, since only recently have I needed to share files on "B".

-Randal