Hi Jack,
Thank you for your message.
Are you still having issues with the validator?
The W3C validator is an external service (http://validator.w3.org/) of the W3C (World Wide Web Consortium - international community) an they restrict requests from specific location (probably according to IP addresses) to some number in the time, so this service is not available all the time (especially when it is used often).
Kind regards,
Richard Sustek