First, make sure you are on the latest iOS update. Update to the latest iOS to get the fixes for memory issues.
Go to the Device Settings, tap Applications, tap manage applications, find the application in the list and open it up. Then Force Stop on the application. While in the same screen press the clear the cache button. Then go back out to the main screen.
Restart your device by powering it all the way off then 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 it installed, disable it and see if that helps.