Chris,

I doubt if this is your problem, but this symptom will appear if your
database is almost full.  Happened to me last Thursday.

The activity log never gets deleted because it exists within the database.
Nothing gets logged when the database is full for obvious reasons.  All you
have to do is extend the database and it comes back.  Of course, stopping
and starting the service doesn't fix this issue.

Bill Smoldt    SSSI
Storage Solutions Specialists, Inc.
www.storsol.com
smoldt AT storsol DOT com