Okay, here's the scenario:

I am in my own mailbox through Outlook 2003.
I have full rights to two other users' mailboxes.
I open the two calendars up.
When I try to move an appointment from one user's calendar to the other
user's mailbox, I get a pop-up error that says:

Microsoft Visual C++ Runtime Libary

Runtime Error!

Program: c:\Program Files\Microsoft Office\Office11\Outlook.exe

This application has requested the runtime to terminate it in an unusual
way.  Please contact the application's support team for more information.

I could copy it, but I cannot move it.  I could move an appointment from
either user's calendar into mine, but not between the two user's calendar.  
It does not just happen on this two user's mailbox, it could be any two
users.  Also, it works fine on one machine.  But the 3 other machine does not
work.  All have Office 2003 with SP2 installed.