action while waiting destroys state

I am not sure if it is just me but I’ve noticed that when the user performs any action on a vaadin page while it is waiting for a previous operation, we get into an invalid state and the app needs to be restarted by opening a fresh browser? Is this a generally accepted issue or am I stumbling upon some dark corner?

This is also the case with the window’s close listener. I have had cases where some sql query takes very long time and the user event does not return back for a long time with the red spinning wheel at the top. At this moment, the user tries to close the tab, but that won’t be allowed since it does not seem to be able to call the close listener. In IE7, this brings the whole browser down and crashes it nicely. Anyone else have had this experience? I am using the latest version of Vaadin - 6.4.2