This concerns a computer that has been on this LAN and working quite well
for years.

Now, every time I try to use Windows Explorer (or any other utility) to
access the WORKGROUP (call it Workgroup XXX,) the workgroup icon appears
under My Network Places>Entire Network>Microsoft Windows Network with a "+"
in the expansion/contraction box the left.  When I click on the +, an
hourglass appears for 30 - 40 seconds, then the hourglass closes, but the
XXX Workgroup does not expand to display the list of computers on the
network.

When I then click on the XXX Workgroup icon in the tree structure, an error
message pops up with "My Documents" in the blue stripe at the top.  The
message reads:

"XXX is not available.  You might not have permission to use this network
resource.  Contact the Administrator of this server to find out if you have
access permissions.

The list of servers for this workgroup is currently not available."

First of all, I have no idea why that error message appears on a My
Documents error dialogue.  I was not in nor had I been in My Documents when
I tried to open the workgroup.

I am the Administrator.  I use the same User ID on every computer in the
LAN, including the one that's giving me trouble today.  I have
double-checked everything I can think of, but find no reason for this error
message to appear.

The computer that's causing trouble does have physical access to XXX through
a LinkSys router, and it is able to access the Internet now.  But it won't
permit me to access XXX like it has every day up until now with no problems.

So, I shall greatly appreciate your help in getting this problem resolved.