If it is the details that came with the original box, they should be ok for the stick. I have no idea why they don't save as the log in details should be saved into the registry in HKEY CURRENT USER/Software/Airnav Systems and should be looked for in there every time you start up. If you don't mind looking into the registry have a look and see it the details are set ok
Did you install the software to program files or the recommended C:Airnav?
Try installing the original software that came with the box first, open up with it, once its working ok then install the new software over the top
Alan