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?

F3) or the entire .blend (Ctrl+S)? – gandalf3 Dec 20 '13 at 20:14