Error Message Feedback

Validating

I ' have a problem with validating my site at http://www.doctoralvik.ru.

Use this link to see validation results. Error 404, but site is working.

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.doctoralvik.ru.

I use "Extended Interface" with "Validate error pages" option and when all is 
right.

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.doctoralvik.ru&charset=%28detect+automatically%29&doctype=Inline&No200=1&verbose=1

Can you help me to solve this problem?

[ Add your message/question here.
  Follow the instructions at
http://validator.w3.org/feedback.html#errormsg ]

Best regards,
Dmitry Youzeptchouk
OOO ALVIK
Russia