Its the navdata.db3 you are looking for Where on your computer is the file just now. Isn it in c:airnav\radarbox or c:airnav\programfiles .
Open up my computer, then click on Vista c:
When the next window opens, click on program files
When the next window opens click on Airnav systems
When the next window open click on Airnavradarbox 2009
When the next window opens click on data, you should now see Navdata.db3
Go to the start button click on it and then computer when it opens up.
click on Vista c: and when it opens click on Airnav Systems,
When the next window opens click on Data
When the next window opens you should see the Navdata.db3 file. delete it.
Now go to the other Navdata.db3 file and drag it across to the one you deleted the file from.
Close down the window and start radarbox and all should be well.
Let us know how you get on
Alan