Parse Error

I would like to premit I'm writing this email only because I could not find any answers on FAQs, reported problems list, Forums or even the web. The problem is: I just validated my web page (http://www.claviusphotography.com/sguardigitali) trough the W3C XHTML validator and received in response it is "Valid XHTML 1.0 Transitional". I'm now trying to validate its CSS too, located at http://www.claviusphotography.com/sguardigitali/style.css but i keep on receving the following error: "Line:0 Parse Error - :". I've tried in any way to solve this error, even trough the use of HTML Tidy, downloadable from W3, nevertheless it seems there's no solution. I'm just asking is the following: if the XHTML of the web page has been considered correct and thus validated and no errors specification were given about CSS: how should I correct the problem? 

I'm thanking in advance anyone who's going to help me in increasing my website accessibility level.

Luca Montanaro
ITALY