Mapping drives after installing NIS

I have seen similar posts here but nothing addressing my problem.

Recently installed NIS on my PC.  Since then I am unable to ""see""  my network drives in Explorer.and my backup sw fails to write to my network drives citing a "password' error.  Previously, I could 'see' and acess those drives.

I have found I can co into "Map Network Drives,"  remap the drives, and they show up on Explorer.  AND, my backup sw can write to the drives without changing passwords.  Remapping is done while NIS is still activated and can access the net.  Every day, when I start up the PC, I have to manually remap the network drives.

I can see no options in NIS that appear to relate to mapped drives.

FWIW, one drive is cabled (cat5) to the router.  The other is attached to the router by USB.

It seems to me (but I know nothing) the firewall is not the problem since remapping solves the problem and passwords are not the problem since remapping solves the problem.