Exchange calendar not quite right

I have a group of 12 users that share a calendar on my Exchange 2000 Server. It is used to see what each of our service technicians are doing on a daily basis. On one user’s computer, whenever someone else in the group adds to the schedule, one day events show as two days long on his Outlook calendar. Whenever he adds to the schedule, his one day events show as two days long in the other users Outlook calendars. Everybody is using Office 2003 Pro. I have gone as far as deleting his Outlook mailbox and deleting him from our AD. The problem still persists. Any help would be appreciated.