I'm having the same problem. I tried to reset and that didn't work. All the JavaScript references appear to be pointing to the right folder.
When I attempt to view background image, I get this:
System.Net.WebException: The operation has timed out
at System.Net.HttpWebRequest.GetResponse()
at nbdc.communityserver.themes.aero.Renders.BG.RenderContents(HttpContext context)
My Url to produce that is:
http://[Server]/Themes/default/AeroScript.aspx?mode=bg&width=1280&height=994&guid=3c50e492-1880-4251-9923-c9d94f4515d1
I can change the background color just fine. I've searched everywhere for an answer, I am running out of ideas.