I have a home network, which includes the following components:

BUFFALO WHR-G54S Wireless Router (and ADSL broadband modem)

MEDION DESKTOP computer, running Win XP Home Edition (SP2) with all security
updates
McAfee Security Centre 2006 (VirusScan and Firewall only). The McAfee
Firewall has been configured to trust the local network.
Windows XP Firewall is turned off (to prevent clashes with McAfee
The desktop computer is hard wired to the router. It is also hard wired to
two printers on LPT1 and USB

MEDION LAPTOP computer, running Win XP Home Edition (SP2) with all security
updates
McAfee Security Centre 2007 (VirusScan and Firewall only).
Windows XP Firewall is turned off (to prevent clashes with McAfee)
The Medion Laptop connects wirelessly to the router

HP LAPTOP computer, running Win XP Professional (SP2) with all security
updates
McAfee Security Centre 2007 (VirusScan and Firewall only). Windows XP
Firewall is turned off (to prevent clashes with McAfee)
The Medion Laptop connects wirelessly to the router

I have Administrator privileges on all computers. UPnP is enabled on the
router and on all of the computers.

I have run the networking wizard on all computers - each computer is a
member of the same workgroup.

The following networking features work well from all computers:

a) Internet connection
b) The network printers
c) Access from the Laptop computers to the Shared Documents folder (and
its sub-folders and files) on the MEDION Desktop computer.

I have enabled Network Sharing for "My Documents" on the MEDION Desktop
computer (and its sub-folders) and I have also checked the box, which allows
network users to change files on the MEDION Desktop computer. I have mapped
the Desktop "My Documents" folder as a drive on one of the laptops.

This configuration, which is intended to provide full access from any
network computer to "My Documents" on the Desktop computer has worked OK for
many months.

More recently, when I try to open the "My Documents" folder from either
laptop (or any files in that folder), I receive the error message
"\\DESKTOP\My Documents is not accessible. 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 Network path was not found."

This problem has occurred within the last few months. I can still open
files in the "Shared "Documents" folder, so I don't think this problem is
related to the McAfee Firewalls. The Windows XP firewalls are turned off.
Furthermore, sharing permissions on the Desktop computer appear to have been
set correctly.

I shall appreciate any suggestions for resolving the problem.