now that I have found my Dem4km.bgl' and recovered most of my Addon Scenaries I am now having my sim crash repeatedly when inbound planes get within about 15 miles. of certain airports. For instance my Twin Falls Idaho airport Addon has always had a serious frame rate problem. but now none my planes can approach it without my sim crashing. Other Addon Airports like my Boise airport have no problem. 
What could be causing this?
JWPLS

Corrupted AI plane textures.

 

Still looks like a FS uninstall-reinstall would be best.

If I do a complete re-install will I lose my addon sceneries and planes?

Also are you saying that this may be caused by AI traffic corruption?

You are better off re-installing everything.

 

No, to fix the AI you need to re-install everything.

 

Too much flying time is being taken up by issues that should be fixed by a clean reinstall of everything.

Cannot make out if you are referring to AI or user flyable planes which are causing your FS9 to crash. If it concernes your own approaches in flyable planes I would want to suggest that you check for duplicate Afcad type files which are well known causes of this specific type of crash.

 

Good luck

Hans