The reason is because you have Pop ups blocked.
Chess has been updated to HTML 5, some other games have not.
When you click to see a players statistics or toplist, there should be a little notification on the top right of your browser saying "Pop-up blocked", simply click that notification and then click "Allow pop-ups from flyordie", that will resolve this issue.
If not, then I suggest switching to a different we browser, I myself use Google Chrome as it's more efficient and quick with loading web pages.
