DVD Not Found: Mystery Solved

Some users reported during 920 beta that X-Plane would sometimes not detect its DVD - a condition that would come and go. Tonight I figured out what is happening.

1. In order to validate the DVD, X-Plane decompresses part of its contents into the preferences folder. Why preferences? There is no good reason - it's historic.
2. X-Plane will create a preferences folder if there is not one. But it does not do that until you quit.
3. The X-Plane installer will not make directories unless they contain files.

So put these three things together: on the first run of a new install, there is no preferences file, so the DVD check fails since the directory that will contain some temporary files is missing. Run a second time, and the directory is there and the DVD check succeeds.

The next patch of the sim will fix this, but in the meantime, if you delete your preferences, leave the empty directory in place!