I would never trust these validators which in some cases don't even validate their own sites. For example type in any of the big websites and sometimes hundreds of errors come up. I often get clients (the ones who think they know a bit about the internet) saying that the site we have designed for them isn't W3C compliant and we then point out that neither is facebook, or twitter, or ebay or even google. For instance ebay.co.uk has 430 errors and 28 warnings. Ignore them. I use google webmaster tools to check the site, for obvious reasons.