CPU usage grows to 100% while baking light

Hi, i am having trouble because in my FPS game i am trying to bake light, but i run out off memory in the process at some point and unity shuts down.I have a 3 level indoor environment(a dungeon illuminated by torches - about 60) and much more outdoors environment - mountains, plains, forests, rivers(made by digging the terrain until reaching the big waterplane underneath the terrain).I tried making it easier for unity -i erased all tress in the map but it doesn't help.Settings:(in unity 5.0.2) - turned down to 0 ambient intensity,default LowResolution in General GI,atlas size 512,no shadows for all light sources.Now it doesn't crash while baking,but the latest errors are now(a few dozens of them):

'Baking Resources' job failed with error code: 3 ('Failed reading Bake Input System file.').

The terrain is very dark, all ground,a lot from mountains. It's an evening-night scene,but this is exaggerated.Basically i don't see where i'm going(even if i tried switching the sun(directional light) intensity to 1(higher than my 0.7 night-setting).And yes,every game object is marked as static.What did i do wrong?I'm about to restart my project