Or is it? A quick peek at markup can reveal a lot!
You might want to ask W3C Markup Validator, too.
Hint: Pick "show source" at the W3C Validator and revalidate. Does the source look the same?
What does the HTML Validator plugin for Firefox say about the validity?
You can evaluate the accessibility also with Cynthia Says and WebXACT.
(More on this topic at Hypermediaa ja elämää -blog. (in finnish only, sorry!))