Most probably the (embedded) skin CSS files have failed to load. You can use Fiddler or Firebug to check your web site for failing requests. I have a blog post showing how to troubleshoot and resolve such problems. You can check it here
Indeed the odd appearance of the grid is due to the default skin not loading. This is because you have set EnableEmbeddedSkins="False". I assume you want the 'Default' skin because you have not specified one. Remove this declaration or set it to true. The odd combobox layout is due to the lack of the skin.
The images not loading is probably unrelated to the skin not loading. I'd check the path to the images.