Here's the situation: my application opens one or more child windows with Show() which allow the users to perform several functions, while also being able to click back to the main application.

In each of these child windows I create an event handler, which fires when a new email is received.

This work fine (the event handler is called) however as soon as the code in the event handler begins to execute it just stops. That is, using the debugger I can tell that the event handler has been fired, but when the first line in the handler's code (and this can be something as simple as 'string s = ""'; ) is executed execution of the handler stops.

Is this a threading issue, and is there something I can do to work around it?

Using .Net 3.5SP1