This is an older thread, but I just ran into same problem and had to do another step beyond what Pete indicates above. I also had to delete "Previous flight" files in the same folder as FSX.CFG. There were also "Previous Flight" files in the Flight Simulator X Files folder in your Documents (aka saved flights). In case this helps others, that's my experience; and for those truly new to all this, in a "standard installation" on Windows 7 here's where those folders are that Pete references.
- FSX config folder: C:\Users\USERNAME\AppData\Roaming\Microsoft\FSX (same as %appdata%\Microsoft\FSX )
wxstationlist.BIN and "Previous flight" files
- Saved Flights folder: C:\Users\USERNAME\Documents\Flight Simulator X Files (same as %userprofile%\Documents\Flight Simulator X Files )
saved flights and their associated .WX files