I have a very simple airport with the following (R23): - One runway (17/35) - Two start points (properly configured for the appropriate runway) - One apron at the end of the runway - A windsock - A small fuel station near the apron Originally I had some errors that were brought up by the fantastic error checker (something sceneGenX never brought up!). So I fixed them. Then I compiled the error-free (the checking) but it failed. I noticed a bunch of weird errors about apron and runway being X meters away from ARP (what the heck is ARP?). The compilation (not the error checker) indicated that my windsock length was too small. I went back and fixed all the issues. Ran the error checker and it came out clean. Then I ran the BGL compiler and it succeeded. This time it did not show any compiling errors. Because I run in a restricted environment I used a DOS window with Admin rights to copy from my restricted account directory to the Add-on Scenery directory (only Admin can put things there). Subsequently I ran FSX, It detected the new scenery and rebuilt its scenery database. I loaded my default flight that is just above the islands near the airport I am building (there is no airport there in FS9/FSX but there is in real life). And then while the flight is loading the whole FSX (SP1 with SDK SP1A) crashes. I get the typical Windows dialog "An error has been detected and the application needs to close, we are sorry. Debug / Close". If I remove the BGL file generated by FSX Planner then my default flight loads just fine. I was having the same problem when I compiled it with ScenGenX. The path to the FSX SDK is properly configured too. What is wrong?