[Samba] Can't connect to Samba server

[Ed]

Hi,
 
I have a small LAN; 3 Win XP clients plus a Samba server.  It was all
working fine till recently.
 
Now, only one XP client can connect to the Samba server.  It does so with no
problems.
 
The other two XP clients cannot connect.  The Samba server shows up in
network neighborhood but when I try to browse it (by double clicking the
icon in network neighborhood) I get a message: \\Smbserver
<file://\\Smbserver is not accessible.  You might not have permission to use
this network resource...  Windows cannot find the network path.  Verify that
the network path is correct..> is not accessible.  You might not have
permission to use this network resource...  Windows cannot find the network
path.  Verify that the network path is correct..
 
I have also tried to connect by mapping a network drive and specifying my
Linux/Samba user name and password.  The message here is "Network path
\\smbserver\pool could not be found".
 
The only thing I see in the Samba logs is in log.nmbd.  I don't know if it's
relevant, but there are multiple messages that all say, in part, "response
packet id nnnn received with no matching record."
 
Why does this work on one XP but not the other two?  What could be
different:
 
Thanks,  Ed