I semm to have the same problem as: http://social.technet.microsoft.com/Forums/en/office2010general/thread/ce07b3fb-6b24-4530-9f98-7c536ed5bc7c
When I close outlook 2010 by clicking on X it seems to close (gone from taskbar) but it is still there on task manager.
When I try to reopen outlook 2010 from taskbar it does not open UNTIL i say kill process of privious outlook 2010 session over the task mananger.
I think it MAY BE related to the problem that outlook 2010 cannot finish the process of sending / reciving mail at my PC because actually one of the mail server is down. But outlook 2007 never had a closing/restartingt problem with that configuration (dead mailserver).
(i have installed office 2010 32bit public beta2 german)
