Windows XP confused by multiple wireless networks
If you use your XP PC in a location with multiple wireless networks, you may find that your XP PC is connecting to the wireless network with the strongest signal rather than your network. You can solve this problem by ensuring XP does not automatically connect to non-preferred networks.
Right click the connection icon
Click View Available Wireless Networks
Click the Advanced button
Ensure that only your network is in the preferred networks box. Now on the new dialogue click the Advanced button
Check that the Automatically connect to non-preferred networks is unchecked.