Distribution/Version: Ubuntu Breezy (x86-64)

(Sorry, poor summary - not really sure how best to describe it!)

Often, sometimes 2 or 3 times a day, when I drag a message from my Inbox (in the
top-right panel of the mail view) to one of my folders (in the left panel), when
I release the mouse button, the drag continues. In fact, however I try (whatever
mouse and keyboard inputs I try) I cannot drop the icon anywhere. The window
manager stops responding to 'Alt-Tab' etc.

If I have another computer available on the network, I can ssh in, 'killall
evolution' and things return to normal, so it suggests that evolution is
blocking the X server in this state somehow. If I do not have access to kill
evolution, I have to 'Ctrl-Alt-Backspace' kill the X server and log back in
(inconvenient when it happens 2 or 3 times a day).

Is there any more information I can provide to help understand and resolve this?