Machine A (2003 Server, sp1) is running SQL Express with FTI.  Querying
the fulltext catalog returns results as expected and the catalog is kept
up-to-date when data is added/modified in the indexed tables.

Machines B and C (Xp Pro, sp2) are running a restored copy of A's
database.  However, I cannot query the fulltext catalog correctly until
I force a rebuild (sp_fulltext_catalog 'name', 'rebuild') but then any
rows added/modified  aren't being updated in the catalog.

Machine D and E running the same thing as B, and it all works like it
should.

What can be going on with this?  I've tried numerous things to narrow
down what could be the issue, but am coming up empty.  After restoring
the database, I've gone and dropped all indexes, dropped the catalog,
and recreated it all - but it doesn't change its behavior.

The indexes were created "with change_tracking auto".

Any ideas?