Recently moved to a high-end WINDOWS 7 desktop. Re-installed FSX and SP2. Everything works perfectly. Custom settings are all maxed out and FPS is still 30+. Only one problem... the livereries on some add-on planes are greyed out, i.e., you can see the fuselage [and wheels, etc.], but that is all. Other add-ons and all default planes show perfectly and look better than ever. Anyone come across this problem??
Thanks,
Pilot Jack.

It sounds like the sim is not seeing the textures.  You might want to double check the aircraft.cfg files of the problem aircraft.

Nah, don't waste time with the cfgs now that we know that DX10 was the problem. (FS9 aircraft don't display in FSX properly with DX10 enabled) For many users, DX10 adds a boost in FPS. So, there's the problem. Looks like if you want the great FPS back, enable DX10 and don't use any FS9 aircraft.