October 16 Windows update screwed up network access

I use Norton 360.  A major Windows update (I am running Windows 7) took place yesterday on both my network computers.  Now I am being asked for a network password for the account "Nobody" (which I never heard of) to assign a drive letter to my NAS drives and am being refused permission to paste material from one network computer to another.  Both are set to share network resources and I have always been able to do that up until now.

This is a private home network.  I am the only user and am, obviously, the administrator for both machines.  I am guessing that the update may have included some sort of update to the Windows Firewall.  Windows Firewall says it is being controlled by my Norton 360.

This is a bit of a mess and I need to get control of my network back!