Missing Schemas

Hi,

We've got a rather odd problem with our PG 7.3.2 production installation.
Everything is working fine on the surface, and has been for quite some time.

Only recently, we have noticed the abscence of any schemas.
We're at a complete loss as to how this happened, or even when.

The databases we run are used purely for web applications, and are
generally only ever accessed locally.
It was only on debugging queries from a third party product that we
noticed their absence.

The product issues queries like:
SELECT * FROM dbname.public.users;

Obviously, the JDBC Driver making the SQL query fails on 'public'.

We have another installation on a development machine that was compiled
from source at the same time.
This machine seems to be OK, so I doubt the production installation
failed in any way.

Does anyone have a clue as to how this may have happened, and an
approach to remedying the problem with a reinstall?
Many thanks in advance,

James.