I was experimenting with texture painting and noticed something really, really annoying.
I spent 15-30 minutes painting, saved, then used the map as a texture. Note that I saved immediately after painting and before setting the object texture.
As soon as I did, it turned black. I couldn't make it go back, so I quit, making sure to not to save the messed up image. When I opened the save, the map was still messed up.
Does it automatically save changes to the UV even when the blend it's self isn't saved?