I have no idea. But here is a segment from the latter half of the help files under: "Why am I seeing inappropriate ads on Chess.com which mentions DNS (Domain Name System):
Is it relevant? I dunno.
...Inappropriate ads may also be showing up on Chess.com for you because of an error in how your computer finds servers on the web. Most people can fix this by running their operating system's "Software Update", and installing any recommended fixes. If that doesn't help (the problem may not be your computer, but your ISP or network), then try using the DNS servers available from http://www.opendns.com (instructions are provided at the website).
If you cannot do either of these because you are at work, contact your IT department and let them know that your network may be vulnerable to the "DNS Cache Poisoning Vulnerability". They may need to update not only your computer and servers, but also their routers and other hardware.
Sometimes when I try to go to www.chess.com I get the error message "Service Unavailable - DNS Failure" and I can't access the site for about twenty minutes. This happens at random times throughout the day and only to this website. I've tried using multiple browsers but nothing changes. Any ideas on how to fix this?