Cycles Material "Texture missing" in render? I spent hours on creating a background with matte textures.

No problem, they show up in the Material and the Texture view: 



Everything works.

Solid view:



Now I tried to render it and got this:



Pink textures all over the place. I have seriously no idea why Blender keeps doing this. I double checked all textures in the node trees, they are exactly where Blender points them at.

Here is the material:



but they just do not show up in the render.

I have no post-processing so far.

Here my lightpath settings:



I hope somebody can help.

Thanks in advance!
Update!

Apparently it has something to do with an out of memory error (since this is just a background for  gigantic scene with hundreds of textures)

As you can see it doesn't render properly when all objects are visible


But as soon as I hide every object except for example a tree that isn't rendering properly, everything works as it's supposed to


Blender gives no CUDA errors though.. I'm really confused. 
I have 10GB or RAM installed and a GTX 550 ti with 1GB btw if that helps

SOLVED

Apparently there was indeed a CUDA out of memory error. It's fixed by just switching to CPU render.

Thanks everyone for their input!!!