Loosing Connection between MN500 & MN520

try this
TCP/IP stack repair options for use with Windows XP with SP2.

Start, Run, CMD, OK to open a command prompt.

Reset WINSOCK entries to installation defaults: netsh winsock reset catalog

Reset TCP/IP stack to installation defaults. netsh int ip reset reset.log

Reboot the machine.

BTW I just did a search at
http://support.microsoft.com/d efault.aspx?scid=fh;EN-US;KBHO WTO for
wireless with Windows XP selected as the product to find most of these
articles.  Some of the articles I already knew about.  I did the search
with 150 articles listed.

The best one for you with detailed directions is "314897 How to set up
your computer for wireless networking in Windows XP".

Here are some more Microsoft articles about wireless.  These are mainly
if your have problems after configuring the wireless connection.

==============================­==============================­==========
Here are the articles I already knew about wireless
==============================­==============================­==========

313242 How to Troubleshoot Wireless Network Connections in Windows XP
330277 MSBBN: Cannot Obtain Access to Files, Folders, or Web Pages With
Your Wireless Network
331950 MSBBN: How to Manually Configure the MN-500 Wireless Base Station
810955 How to Install, Connect, and Configure Your Wireless Base Station
810960 MSBBN: Wireless Connection Repeatedly Stops Working
810962 MSBBN: Wireless Base Station Is Not Detected Through a Wireless
Adapter
811039 MSBBN: Installing and Configuring the Wireless Base Station MN-500
817463 MSBBN: HOW TO: Configure a Wireless Access Point

==============================­==============================­==========
Here are the ones I found doing a search for wireless with "Windows XP"
as the product.
==============================­==============================­==========

821371 Capabilities of the Internet Gateway Device Discovery and Control
Client and of Universal Plug and Play
302088 Wireless network adapters may lose connectivity when they appear
to be functioning
303607 Bluetooth Wireless Device No Longer Functions After Upgrade to
Windows XP
305616 Wireless Networking May Not Function When You Use the "Safe Mode
with Networking" Option
309369 How to Make Your 802.11b Wireless Home Network More Secure
309495 Problems with Windows Installer Over Wireless Connection
314801 Wireless Modem May Not Start
323183 Availability of Windows XP Service Pack 1 Support for Bluetooth
Wireless Devices
324024 Wireless Network Adapter Appears as Disconnected
328647 The Wireless Connection Icon Shows "Unavailable" After Your
Computer Resumes from Standby
810020 "Wireless Connection Unavailable" Message After Computer Resumes
from Standby
815485 Overview of the WPA Wireless Security Update in Windows XP
821400 Wireless Network Adapter Intermittently Loses Its Connection to
the Server
821442 You cannot connect to a wireless access point with the Wi-Fi
Protected Access update installed
826239 Small Delay in Logon to Network When You Use a Wireless Network
Connection
822725 60-Second to

I've uninstalled it, but now it doesn't do anything.  I
guess I don't know how to configure it without the
utility.  I tried to reinstall the utility and it keeps
faulting and telling me to reset the base station.  I've
done this numerous times but nothing helps.  I'm about to
take this thing back.  Can you send or post a Word file
giving line-by-line instructions for setting it up via
Windows XP?

networking utility has

Uninstall the Broadband networking utility.  And use Windows XP to
configure the wireless connection.  The Broadband networking utility has
some issues like the one you just mentioned on Windows XP.  Seeing as
Windows XP is the first OS from Microsoft to fully support wireless
networking you can use Windows instead.

If I enable security, then I get a "incorrect wireless
security key" failure.  I input my own 64bit key in to
the base station and then into the wireless adapter (via
Network Utility) and this is what happens.  The 802.1x is
disabled as far as I can tell.

other 802.11b WAPs &

THe only time to enable 802.1x authentication is when you are using WPA
which the MN-500 doesn't support as well as all the other 802.11b WAPs &
routers that were released at the same time or earlier.

Are you using the Broadband Network utility to enter the WEP key then?

Is the computer running Windows XP SP1?

They both are running XP.  SP1 is a service pack, right?  
I'm pretty sure my system is up to date.  How can I go
about to see if is SP1?

If you have SP1 you need to disable the 802.1x authentication.  It's in
the properties of the network connection on the authentication tab.  You
uncheck the box and the problem goes away.

I've read about that and looked into it.  That field is
grayed out.  I think because I have disabled the
security.  I did that because it wasn't accepting my WEP
code.  Should I re-enable the security and uncheck that
field (if it is checked)?  But the 64 or 128 bit code
isn't accepted.  What to do about that?

authentication.  It's in
authentication tab.  You