Texture Pitfalls

There are several ways to crash UED if you are not careful when deleting or renaming textures, they are:

1. Deleting a texture that is in use - if you delete a texture that is in use, UED will crash if you try to save or look at the texture in the 3D view (this is really tough, you're moving around and all of a sudden it hangs). The correct way to do this is to first make sure that the texture is not in use Anywhere in the map (including surfaces you can't see!), and then delete the texture. If you have used the texture a lot and are not sure where all it is, then you can use the texture replacing tool, or test if you have gotten rid of the texture entirely by performing a texture cull, which will also remove the texture for you.
2. Delete a texture and then rename another texture to be the deleted texture's name - I'm not quite sure of the specifics, but if you want to do this delete the old texture, save, and re-open the map, then rename the other file. Better yet if you are simply replacing a texture import the new one right over the old one.

The material here is duplicated Crashing UnrealEd, which is getting long (what a surprise). Maybe link this from there & move texture-related things here – Tarquin