I go to the host/module page as host. I click on a pencil (edit) of a module. It falls back to the host/module page and doesn't get to the edit page. It displays the  message at the top "Critical Error - object not set to instance of an object". I look at the stack trace and it point to a deleted skin? I look at the page source. It doesn't point to the deleted skin. The skin must be used by the edit page or is being mapped to the page dynamically? I change the host/module page settings to use a build in dnn skin. I click on the pencil and it brings up the edit page fine. So that tends to lead me to believe that the code in the skin selected the edit page skin since a change of the skin changed the behavior.

How do I fine where this deleted skin is being used? Why is it being referenced? What db tables would be involved? Is there any utility that maps pages/modules/skins? Is there any find/replace for obsolete skins? Why did it let me delete a skin apparently still in use not not map the deleted skin to a default?