Lightmapping problems

Hi All
I have a scene which I lightmapped to get some ambient occlusion in, all was fine and it looks nice, I then noticed that some of my objects that I need to move were marked as static so I checked static on those cleared the lightmapping and rebaked, now those objects have awful black textures over them, seems clearing doesnt actually clear the lightmap uv channels and the objects are still being rendered with the light mapping shaders.

I did try and go through each object and set the Lightmap index to 255 which gets the lighting back but now means the object doesnt cast any shadows. Can someone please tell me the correct way to reset the lightmapping on a scene back to nothing so I can start afresh as it seems once you bake something it is a nightmare to rebake it all, I must be doing something wrong, any help would be great.
Thanks
Chris

Did you find an answer to this?

i have found the 255 trick worked for me, but so did the clear button… the only thing coming to mind is when the new lightmap was baked the black objects had an index number that wasnt there, so no lightmap where it sais it should have on? or possibly -0 or something, if there was no map in that index then i could see it being black, and if you did a select bake it would re assign index numbers and maps to the re baked and if something was in the 4 slot in the lightmaps or somthing and now you only have 2 maps, everything with index #4 would be black as now that slot is empty/non existent. hope that leads you in the right direction