Missing Activities in Outlook XP

[Christopher Chapman]

Using the Activities tab, I often will review or search for email for a
specific contact. Somewhere along the line, my Activities got lost or
disconnected. I am only able to find a couple of email messages from
contacts that I know I have dozens for. All my contacts exhibit the same
deficit. I can find these missing messages by searching in the individual
folders, so I know that they exist.
This resembles a missing or broken index problem. Is there any way to
re-index my message file?
Any ideas of how to solve this problem?
Thanks in advance,
Christopher