Whats causing syncing issues in Outlook 2007 with 2003 shared calendars? The problem is a user has multiple calendars they have access to and when they go to open a calendar, it times out with error message "The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action". We're on a corporate environment that is connected to an exchange server. So I was told there was some compatibility issue between Outlook 03 and 07 and that in order to fix this, the people using 03 need to be upgraded to 07. So what is the actual issue? Would someone be able to shed some light here?