disappearing contact

[Susan]

One of the partners in my firm has reported that
individual, random names keep disappearing from his
contact list. I can't explain it. I've checked to see if
he erroneously entered it/them in a differentlistin error
but no luck. Beside the obvious (he accidently deleted
them) has anyone come up against this problem and can
recommend how to troubleshoot?

Is there a limit on the number of entries you can make in
a contact list, for instance?

thanks