Is somebody familiar with the problem that only the inside of the airplane is shown?

This happens after you load the airplane from the "skeleton" form in the menu. If you leave the NGX hanging on the menu for too long, it becomes a skeleton, like the one above. This is a known issue and cannot be fixed. Just choose another aircraft then come back and select the NGX and you should be fine.

There is a simple but very effective solution for this issue:

Just add the line ...

HIGHMEMFIX=1

 ... into the "GRAPHICS" section of Your fsx.cfg and the problem is solved!

 

This is also pointed out at the NGX Introduction manual at page 12 [by the way and just one minor note: Although it is suggested at the Intro manual too here, i would add HIGHMEMFIX=1 but i would not set Texture Max Load=4096 (rather use 2048 here, but that's another topic, so let's leave that for now)]

 

So, to sum it up:

Just add the HIGHMEMFIX=1 fix to the "GRAPHICS" section of Your fsx.cfg and Your skeleton planes will belong to the past!

Cheers, Christoph