There is already a thread going on about this with more information...
Clicking the window has nothing to do with it. The problem is that the client fails to connect to the next zone server, and instead of waiting gracefully, the client does whats called "busy waiting" (instead of yielding the process), and that causes the program to become unresponsive to everything else. Then entering input into the game (clicking) causes windows to realize that the program has become unresponsive and you "see" the crash that has already happened.