Funny thing was, after debugger disconnected from Tbird, the UI was no longer hung. Very strange. I know that when connecting the hung was real, because MSVC reported "The application you are connecting to is not responding".
Alex is this gone in version 184.108.40.206? http://www.mozilla.com/thunderbird/releases/220.127.116.11.html if it still happens test a trunk build where it may be fixed. http://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-trunk/ Please report results in this bug. Also, please set the version information. other hang bugs - Bug 324196, Bug 324325, Bug 340647
I have a feeling that this was due to my specific setup at the time.