At this point, I would remove all addons and systematically reinstall them, to find the problem. Make some notes as you reinstall.
This is obviously a conflict with addons. I suspect it is caused by a GUID number duplicated by an addon. For example, a GUID for a windsock could be compromised by using the same GUID for another type of object. Just a guess, as I do not have that combination of addons.
Don't think GEX is not causing problems, as it may well be the source of the conflict, as could any of the addons you have.
It could also be caused by a bad airport bgl. In the past, I have had issues with bad airport bgls causing problems at scenery areas many kilometers away. So the problem may not be at EHAM at all, but at some other airport ( which might explains why such a large exclude rectangle is needed).
I don't think you'll get any more help than has already been offered. It's very hard to solve these types of problems, as no one else has your combination of addons.
Dick
Dick, I thought my combination was rather standard. But I agree most tend to use rather UTX and much less SceneryTech. AmsterdamX and GEX Europe are very popular though. Anyhow I'm very much thankful for your time and thoughts that you, guys, shared in my thread on this rather technical forum. Besides, I've learnt something about tip of the fsx scenery iceberg.

Thanks,
Sabre.