Looking at your menu.css file ( menu.css ) it looks like the paths to your background images are wrong.
Where you have (for example) something like:
background-image: url("file:///Joslin MBP/Users/steve/Sites/sdj/gallery/CSSMenuWriter/cssmw_images/menu_bg_l.jpg");
it should read:
i.e. in all such lines you should replace:
You could do a search & replace to easily do this.
The chances are that this is happening because of the way that your site is defined in Dreamweaver. Check (Site > Manage Sites > Edit > Local Info) that you have set the 'Links relative to' to 'Document', and not 'Site Root'. This will prevent path errors like these in the future.
In the meantime you can either redo the menu, having changed the site definition 'relative to', or just change your menu.css to show the correct paths.
Post back if you have any queries.