Were any of the addons in the area where you have this problem ??? If you only see this in one area I think the problem is a Scenery conflict. For some reason that M$ only knows the answer to is that when you add new scenery using the library setting then the add key it puts the scenery at level 1 which means it is loaded first then the default scenery gets loaded and puts its scenery right on top of the new scenery. Sometimes all you have to do is to put the new scenery at the bottom of the list, so it gets loaded last. This usually solves the problem. but not allways. You might have to use flatten and exclude switches to remove the unwanted scenery.

If you decide to uninstall and reinstall I would add the new scenery one at a time then check to see if the problem is there. By doing this you will know which scenery is causing the problem and where you will need to put the flatten and exclude switches at.
Always check the readme files that usually come with any new scenery. Most scenery designers are aware of this and will give you the needed flatten and exclude switches to take care of the problem.
I have an addon scenery that I had to use flatten switches in and the designer provided them in the readme file. 8)