I have baked a high res normal map to my low poly mesh, when i switch to textured mode i can see the map applied in it’s blue/purple/pink colours, but when i render it looks like the image below…all white and black…
well as your not supposed to see the purple of the map in textured mode, just the effect, i would surmise, that you plugged it in wrong.
Is the normal map set to non color data? Are you using cycles or BI? Can we see what your material settings are?