i had occasional crashes on launch with the skybox plugin. i'd say like 5 to 10% of the time i clicked the .exe, it would crash immediately
forget if there was an error of if it just crashed out, its been a while
but i clearly remember one time where it crashed like 10x in a row
when i gave ppl configs with it, they complained about similar issues
stopped using it, never had any crashes on launch since (unless files/textures are missing)