Read the complete post at http://blogs.msdn.com/mhpta/archive/2006/12/01/windows-support-post-wsp-you-receive-an-error-message-when-you-try-to-perform-any-editing-tasks-or-you-must-click-to-enable-the-compose-frame-in-outlook-web-access-from-a-windows-vista-client.aspx