Re: first chance overflow
A first chance exception means an exception has been thrown. A second chance exception means that a thrown exception hasn't been caught, so the app will crash or the debugger's Exception Assistant will be invoked.
The VB application framework provides an UnhandledException event you can handle to catch any unexpected exceptions. It's best to exit from that event handler unless you can confirm that the app is still in a valid state, but at least you are able to log the issue to help you work out where and why it occurred.