First, make sure you are on the latest game version and OS update for your device. Go to the Device Settings > Applications > Manage applications, find the application in the list and open it up. Once you have found the application, force Stop on the application. Make sure to clear the cache as well.
Restart your device by powering it all the way off then tap back into the application, and try again. We have heard of applications called Dashlane, Smart Guard, Avast, AVG, AICP, mC+, Ad Guard and Ad-aware that caused abrupt freezing and closing. If you have one of these installed or similar, disable it and see if that helps.
Make sure that you have at least 2 GB of free space on the device. If the device storage is less than 2 GB try deleting files or unused apps from the device to free additional space.
If you have done all this, try playing the game in airplane mode. If you're successfully able to load the game in airplane mode, this may be a network issue we can work with you to fix.
Support can alternatively be reached via Support@mobilityware.com or via the link below: