Crash after calling StartActivity numerous times

I've got 3 main views of my application, all of which are held by separate Activities.

I use a method in the base class of all this activities to switch back and forth between them. However I'm getting a crash after 8 switches.

I'm doing the view switch in this method: switch (viewModel.CurrentTerminalViewTypeToDisplay) { case TerminalViewTypes.AdvertisementScreen: break; case TerminalViewTypes.OrderOnTab: StartActivity (typeof(OrderOnTab)); break; case TerminalViewTypes.CashCloseTabScreen: StartActivity(typeof(CashClose)); break; case TerminalViewTypes.ViewTabs: StartActivity (typeof(ViewTabs)); break;

Anyone seen any problems like this? Should I be pausing the current activity somehow before switching?