Please, try to perform the following activities:
1. Make sure you have the latest version of the flash-player (the version should start with 12.0).
2. Clear the cache.
3. Enlarge the cache: click the right button of the mouse on the game window → choose Settings → click the tab with a folder depicted (Local Storage) → set the slider to the Unlimited value.
4. In case the problem persists, try to use another web-browser.
If you still experience the issue, please contact our Support Team.