Davy, just out of curiosity... Do you have some kind of case or screen protector over the screen of your phone. When I first started playing, my ipad was in an Otter Box case. The built in screen protector did not allow me to use the touch screen function of the game as well as it does now, with the case off.
Stu, I have the same issue getting booted when jumping in the tank or hitting the chat box. I have started rebooting (hard reboot) routinely and it seems better now.