Validator availability

Hello.

My friends tell me that W3C has a realy handy tool.., all website owners 
should use once in a while.

I am trying to check the site http://www.turkish-property-world.com via 
http:// or https and am getting the following error:

500 Can't connect to www.turkish-property-world.com :443

I had check and validated 3 days ago and had no problem, but today when I 
click the logo backlink on our website footer it is not working.

When I delete the .htacces file it validates, but when I upload it back we 
see the error. I have double check the deny ip's to make sure that was not a 
blocking problem.

Other than that am I doing anything wrong.

Thanks for your help.

Kind regards
RaziDaz