I am having the exact same issue as discussed in this thread: Why does this texture appear fine in material view but appears pink in rendered view?
The image file is not missing - I have used "find missing files", as well as assigning and unwrapping again. The image shows up in the 3D view but is only visible as pink in the render view. I have exported the file from PS as a TIFF with alpha. Is this a bug or am I and Sarsha W doing something wrong?
I'm running Blender 2.78a on a PC.
BTW, I've been going step by step from this tutorial, and the alpha channel texture is the only one with this problem