Editor crashes when I try to import a scene

OK, I’m extremely new to the unreal engine…
I’m trying to import a scene, I’ve tried importing different things, a castle, a car, some mountains, etc… in different formats, both PBX and obj.
no matter what I import, its tarts loading then at the end the editor crashes… I’m using the engine 4.14.2,
Any idea whats going on? how can I import stuff into my level, also is it possible to import content from Bryce 7…

Any help would be appreciated…

Thanks.