It would greatly help to fix this bug if you could download and install .Net SDK from Microsoft. Since we unable to reproduce this bug we are asking our users for help.
The SDK can be downloaded from:
http://www.microsoft.com/downloads/details.aspx?familyid=9b3a2ca6-3647-4070-9f41-a333c6b9181d&displaylang=en
It includes a .Net debuger tool DbgCLR.exe, which should be used to run VNC Manager. When run under debugger, in case if VNC Manager crashes or hangs up-on remote logoff it will be possible to get to know at what point the crash occures.