Normal tangent map in blender 2.5

Hi EveryBody !

I did a lot of bakings in Blender 2.5. I mean between low and high resolution meshes. It was OK.
I recently used the /3GB switch because Blender crashed when increasing the resolution. Blender no more crashes but the map that is displayed in the UV Image Editor is black and gray. There are no more colors (blue … and black).

Any help ?

Many Thanks !