OL2K User not receiving all email.

One of my users is not receiving all of her email. Symptoms, other than no message, are not consistent. She will receive email from some staff, not from others. She will receive email from outside sources, not from others. The next day or the next 1/2 hour, the order may change. Those she could not receive from, she now can. Those she could receive from, she now cannot.

She seems able to reply and send fine. I can’t pinpoint a consistency in the problem.

Any ideas?