Operating system and graphics card
Broken: (example: 2.69.7 4b206af, see splash screen)
Short description of error
When i create an object, switch to texture painting and add a texture paint slot, then a material gets created where the texture node is not connected with the diffuse node.
This means you can do texture painting at the added texture. And the changest that you do at the texture will show up in the viewport. But you cannot render it. The material is missing the connection to the texture. Which you have to fix by hand then.
Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
Switch to Cycles, delete standardcube. Create cube. Switch to Texturepainting. Add Texturepaint slot. Switch to Compositing layout. The texture node has no connection to the diffuse node.