From: "Rich Gauszka" 

It could just be that another wireless network is in range and braodcasting it's ssid

http://support.microsoft.com/default.aspx?scid=kb;en-us;811427&Product=winxp

When your Microsoft Windows XP Service Pack 1 or Service Pack 2 (SP1 or
SP2)-based Wireless Zero Configuration (WZC) client computer is in the
proximity of two wireless access points, and one of the access points is
broadcasting its Service Set Identifier (SSID) but the other is not, your
computer always connects to the access point that is broadcasting its SSID.
This occurs regardless of the preference order of the networks that are
configured on the Preferred Networks list.

Additionally, when your computer is connected to an access point that is
not broadcasting its SSID, and another access point that is broadcasting
its SSID is enabled nearby, your computer automatically connects to the
access point that is broadcasting its SSID.
----------

I doubt not broadcasting the ssid helps with security.
http://www.microsoft.com/technet/community/columns/cableguy/cg1102.mspx
Configuring hidden wireless networks is used as a security measure to
prevent malicious users from detecting and attempting a connection to a
wireless network. However, the SSID is included in other types of wireless
connection management frames and is easily discoverable by either capturing
wireless management frames or using tools available on the Internet.


"John Beamish"  wrote in message
news:op.tl4juxbpm6tn4t{at}dellblack.wlfdle.phub.net.cable.rogers.com...
> V's machine is suddenly having wireless problems.
>
> Wifi Router:  Linksys WRT54G v5
> Her machine is a Compaq with XP; I've also got a Dell D610 corp machine
> with XP to compare results/settings with.
>
> Her machine suddenly cannot see the router unless it is broadcasting SSID.
> The Dell machine has no problems when the router is (or is not -- the
> usual set up) broadcasting SSID.
>
> I've changed channels.  No impact (still needs SSID broadcasting).
> I reset the router and brought it back to the config "last known
working"
> with V's machine.  No impact.
>
> Her machine is updated *fairely* regularly with MS patches.
>
> The corp Dell machine is quite tightly locked down so MS updates/patches
> are pushed through on a very selective basis.
>
>
> Any suggestions will be greatly appreciated.

--- BBBS/NT v4.01 Flag-5