I have a bug report issued at connect.Microsoft.com pertaining to Activity Monitor spawning a modal dialog box behind SSMS when it gets unexpectedly disconnected from server. Because the modal dialog is behind SSMS, SSMS is totally unresponsive to the UI and you have to do some tricks to be able to see it and dismiss it.
If you have this problem too, please up vote the bug.
https://connect.microsoft.com/SQLServer/feedbackdetail/view/944856
