Outlook 2000 Calendar problems with E5.5

The client is running windows 98 on a laptop and complains of two problems.
1. That people are unable to view their free and busy information. Not that it doesn’t show up but that it is inaccurate and that appointments are double booked.
2. That appointments randomly disappear.

I really think this is a user related problem. The user is a senior vp and is adamant that they are not the source of the problem. Has anyone seen theses issues before?