It depends on the skin. I frequently have skin templates which change behavior based on the page they are on (home page versus portal page for example).

Is it possible that the skin has two templates, one with an image header and one without and the former is selected on the page where the image appears, while the latter appears on other pages (perhaps because it is the default)?

Nik

A skin can have any number of templates. Typically, a skin will have a template for the Home page, one for general Portal pages and one for Admin pages (i.e. pages where administrative tasks are performed or when content for a module is being edited). The skin selection for a page is in Page Settings under the Advanced Settings section. When you see the skin names in the skin selection drop down list the format is the name of the skin followed by the name of the template.

For example, the default skin is named "DNN-Blue" and it has templates "Horizontal Menu - Fixed Width," Vertical Menu - Full Width" etc. This results in entries in the skin selection drop down list such as "DNN-Blue - Horizontal Menu - Fixed Width," "DNN-Blue - Vertical Menu - Full Width" etc. 

Nik