I am trying to delete a layer in my drawing, but I get the error "Unable to delete layer. A layer cannot be deleted if it is active, referenced by another element, or contains some entities, or Layer 0 or Defpoints." If I type "Clean" in the cmd window, select "Show referenced entities" , then I can find the layer under "Layers" and its note reads "This layer cannot be deleted because it is currently referenced by: entities." If I then make that layer the only visible layer, the model screen is completely blank. How do I find these invisible entities that this layer references? I want this layer deleted! It shouldn't be this convoluted.