strange result diffuse/normal map

[Rchv]

I was experimenting making a normal map in Photoshop (with Nvidia's Normal map filter), and using it instead of a bump map. Rendering the normal map and diffuse map separately delivered expected results, however rendering the two combined gave a weird result (see images).

The normal map is inserted in the Bump/Normal map slot in Texture settings. Not sure what to set the Bump/Normal map Type to, Explicit Normal type was the only one of the normal map options that showed effect in the render. Both the diffuse map and the normal map are Object mapped with Cube Projection.

I don't understand what goes wrong in the final render with both diffuse and bump/normal enabled, any ideas?

[bdancer]

Could you please send me a test scene?