It is possible that you don't have the required software to play our games. Make sure you have the latest version of both Adobe Flash Player and Adobe Shockwave installed on your system. You can get both for free fromwww.adobe.com.
You could also have some sort of ad-blocking software that could prevent the game from loading. Make sure to turn these off when inside a game room.
A good place to start is by logging out and clearing your browser cache and temporary files. Then log back in and try to play.