Very Computer

We are running merge replication on SQL7. Totally there are 8
publication-subscription pairs created, all of them are listed under
Replication Monitor/Agents/Merge Agents. However, since last week, One
of publication-subscription pairs listed under Replication
Monitor/Agents/Merge Agents was automatically removed during midnight,
but this publication still listed under Replication
Monitor/Agents/Snapshot Agents, subscriber is still listed in the Pull
Subscription under subscribed database, and publisher is still listed
in the publication under the publishing database. Any ideas why this
might be?  I sure would appreciate your help.