If you are using a Bullet2HP for your internet
access and upgrade your browser to Firefox 4 or the latest version of Chrome you will find that every time you change stations you will have to fill in the "Lock to AP MAC Address" field before you can do a "change" and "apply".
To fix this problem you will need to go to the Ubiquit Support Page
and download the latest firmware, v3.6.1. Set Product: to IEEE802.11a/b/g Solutions, Model: to Bullet2HP and Available Firmware to v3.6.1 then click download.
Install this firmware from the System tab.
A significant change for world travelers included in this firmware involves removing the ability to change the Country Code from the GUI. It can still be changed by modifying the configuration file.