LS-WXLD92 is "there", but Windows Security is blocking access

[lancer]

For no apparent reason, I can no longer access my mapped drives from Windows Explorer.  I can log into the LS-WSLD92 directly via IP address from a browser using the Admin/Pswd that works (and hasn't changed in years), but when I run NAS Nav 2, then Browse shares, a Windows Security dialogue box opens and asks for the password for admin.  I enter the same password I used to log into the NAS via the browser, and I get the following error message "\\LS-WXLD92 is not accessible.  You might not have permission to use this network resource, etc etc etc"

any clues how to fix this?