Outlook 2000

I users having issues using the Invite Attendees option in Outlook 2000. I have installed the window updates and also uninstalled and installed office. After setting up the appointment and entering the attendees address the Windows error box appears to send the error and then Outlook will close. When they try to accept an invitation they are receiving a run time error message; Program: C:\Progra~1\Micors~2\Office\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.

Any suggestions will greatly appreciated.

Mary