Computers acquire IP address from wrong WLAN.

Hi,

Odd problem with a couple computers -- one laptop, one desktop, both with XP
Pro sp2.

Topology:

PC . . . . . D-Link 524 (as access point) . . . . . Laptop
|
+----LAN----Sonicwall (firewall/DHCP)---Internet

This problem started happening recently, when a neighbour set up an access
point. Both the PC and laptop were set to automatically connect to our
network (GC) but to NOT automatically connect to the neighbour's (linksys).

When the computers power up, they get an IP address from the linksys DHCP
server (192.168.1.x), but say that they're connected to GC. The problem is
that they can't talk to anything on the GC network because our network subnet
is 192.168.100.0/24.

This happens consistently when the neighbour's linksys is powered on.

Generally, by doing the right-click->repair option on the tray icon, a valid
IP address is obtained from our DHCP server. "ipconfig /release", "ipconfig
/renew" does not work prior to the full-out repair operation.

If I statically configure an IP address instead of DHCP, there doesn't seem
to be a problem connecting to the internal network. However, the Sonicwall
then doesn't route traffic out to the Internet -- and I don't have access to
the Sonicwall -- so using a static IP address is not currently a viable
option.

Has anyone ever seen anything like this? Is there any way to solve this
problem, keeping DHCP turned on?

The people who generally use the PC are a frequently-changing group and a
good number are not technically savy, so asking them to repair the network
every time they turn on the computer is also not a realistic option.

Thanks,
James.