This is an age old problem. In a very brief nutshell, 95% of the time it's due to a duplicate object library installed on your system, and based upon the textures associated with the hanger objects, most likely an old EZ Scenery library. I won't go into detail right now, but here's how to verify whether or not this is your issue.
Locate the following texture
ga hanger ss 3a.dds
When you find the texture, make a copy of it and then add ".off" after the name of the original texture. Now move the copy to the texture folder under the root FSX directory. Make sure the name of the texture that you move is "ga hanger ss 3a.dds"
Now see if the hangers look as they should. Report back here with the results and we will proceed from there.
By the way, I've never noticed a difference or have had any problems regarding where my object libraries sit relative to my scenery libraries. I've had my object libraries all over the place in the past without any problems.
Steve