I think it might be some kind of global you can only do so much with single esm limitation. When I load into the game in the wastelandNV world space it crashes to desktop. It just started doing this...
If I load up FNVEdit and check for errors I get this but I am not sure exactly how to track down what it means.

[00:00] DATA - Flags ->
[00:00] Above errors were found in :WastelandNV "Mojave Wasteland" [WRLD:000DA726]
[00:00] Above errors were found in :GRUP Top "WRLD"
[00:01] Above errors were found in :[01] IWS-Core.esp

Maybe this is causing it.
Anyone know how to track this down and how to resolve it?

edit: Just to clarify, the mod that I am working on adds tons of new spawns to the wasteland as well as hefty helping of idle markers.
hmm it seems as though the crash is limited to the New Vegas area. I wonder if its possible that its crashing simply because I have too many spawns there now.

I don't know what the error means, but I got it as soon as I added a marker to the Wasteland. I tried to fix it by redoing/moving the marker and it didn't go away so I concluded that it was commenting on something else entirely and not what I'd done. It doesn't cause any crashing or weirdness in the mod I'm building. We need JustinOther or Miax to wander by.

I found the error. It was a simple mistake with derived spawn list pointing to the wrong thing.. ><
So much time wasted ...