Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
If FSX works fine, then I guess there could be an issue with the C-47 itself.
If you have saved your own start situation with the C-47, and marked it as default situation, and if something is wrong with the aircraft, guess this type of message might be the consequence. You could try to locate that "homebuilt" start situation, and delete it.
Blue skies
When I see that error it's usuall the panel or even air file. FSX is trying to load it and something is missing. Simply bypass all that by deleting the folder fro, airplanes folder, download the fresh file and install it again.
