Personal appointments disappearing

[JasonC]

I have recently setup a new member of staff, after an appointment that she
creates has passed it disappears from her calendar though appointments that
she is an invitee for stay in her calendar long after it has passed.

I have tried unticking cached exchange mode to no effect and do not want to
backup her folder, delete her account and then re set it back up again except
as a last resort.

Can anyone think of anything else I can try?

Thanks