"URL not supported by this version" error on DOCTYPE

I am new to devloping .mobi sites. I went through the mobiForge training video and am giving it a try. I downloaded the 110.zip template on mobiForge. When I test that file itself in Firefox using the HTML validation extension, I get the error "URL not supported by this version", referring to the DOCTYPE declaration there:

<?xml version="1.0" encoding="ISO-8859-1"?>

Then it says "DTD did not contain element declaration for document type name". So there are 55 more errors because it doesn't recognize any of the elements. Is this an old DOCTYPE declaration? I don't know much at all about XML, so I am really lost here.