Outlook 2000 and disappearing meetings

Hi, support Microsoft Outllok 2000(Corporate install) for a group of admins and the most comon complaint I get is that there bosses meetings disappear of calendars for no reason. I have checked microsofts web site and tried thier sugestions such as Local-vs-server cache. Since they all have Outlook 2000 this shouldn’t be the issue. Have any of you have had similar experiences? Any ideas of things I can try?