I was kind of blaming my megascenery as well.
But did you have a go at reactivating the megascenery?
Any idea FSDT on how to edit my settings so that I can run both sceneries?
I'm running MegaSceneryX SoCal with KLAX and it works fine on my rig as long as I make sure to keep MSX SoCal on a lower scenery layer than KLAX. Also make sure the mesh complexity and mesh resolution are set to the correct values, being 100 for complexity and 5 for resolution. And of course making sure you dont have any duplicate AFCADs from another scenery package or MyTraffic X.