I have several users running Outlook 2003 (using Exchange 2003 server), one of whom shares their calendar as they organise meetings. The other Outlook 2003 users can view the calendar and double-click on the appointments without any problems.

The other users who are still running Outlook 2000 SP3 can view the calendar, but when they double-click on an appointment receive the error: "Can't open this item. Unable to open free/busy information"

I have run "Outlook.exe /cleanfreebusy" on the user who owns the calendar but this hasn't resolved the problem.

If anyone has any solution I would be most grateful.