System Information
Windows 8.1, NVIDIA GeForce GT 630M with 2GB Dedicated VRAM

Blender Version
Broken: 2.75a c27589e

Short description of error
I have mixed a several number of noise texture with mix rgb node and connected to a bump map. If the number of the texture nodes reach a certain number (about 27 not allways the same but maybe depends on the refreshing of the memory, i dont know...) the material change to black (the bump map is also black if I check with the Node Wrangler addon's viewer node). The bug appears in the viewport with render shading mode and also if I render the image. It's also there if I conect to the displacement output. If I connect to the bump map node and the displacement output too the problem goes with less textures. It doesn't matter if I use CPU or GPU render but with the OSL it's completely okay. If I used Musgrave texture the bug was still there. But if I connect the textures to a shaders color input in any cases it works fine.
Actually I don't know if it's a bug or an official limitation but I havn't found anything about it on the internet.

Exact steps for others to reproduce the error
In the attached .blend file just connect or disconnect a few texture node to see the bug.