Find attached what i mean about missing jetways and in the background missing buildings.
Ok, you are not missing any buildings: you are missing *parts* of them, which means, it doesn't have *anything* to do with installation, Addon Manager, Couatl, antivirus or anything like that. If it was, you wouldn't see anything.
Buildings with missing pieces, if you are not enabled any of the "Compatibility" options for the FSX.EXE (see my previous message) can only be caused by a wrong tweak in the FSX.CFG or a video driver issue.
You might try deleting your FSX.CFG file located at %APPDATA%\Microsoft\FSX, and let FSX rebuild one with default settings, maybe it's a tweak gone bad.
When you restore the FSX.CFG to default, be sure to re-enable the "Force HD textures" option in the Addon Manager, otherwise KLAX will look blurred. The KLAX installer automatically sets it but, if you restore the FSX.CFG, you have to set that option back.