There is a WARNING for your page:
Line 196, column 16: character "<" is the first character of a delimiter but occurred as data
And CSS fails on  the same line:

Please, validate your XML document first!

Line 196

Column 18

The content of elements must consist of well-formed character data or markup.

I think this is because CSS validator and XHTML validator use different settings on XHTML validation.  Maybe you should report it as a bug .

ideas whizz

Michael Tichenor wrote:

I attempted to validate a page of mine ( ) and the validator gave an error saying to "validate your XML document first". It's valid XHTML, and it choked on a javaScript function just like every other javaScript function on the page. The validator is supposed to ignore javaScript, no?