Transaction wraparound problem with database postgres

Hi!

My database cluster has just stopped working. I get the following message:
psql: FATAL: Datenbank nimmt keine Befehle an, um Datenverlust in Datenbank »postgres« wegen Transaktionsnummernüberlauf zu vermeiden
TIP: Halten Sie den Postmaster an und verwenden Sie ein Standalone-Backend, um VACUUM in der Datenbank »postgres« auszuführen.

I did as suggested, stopped tzhe postmaster and started a single backend on database 'postgres'; I issued a "VACCUM" there.
su postgres -c "/opt/pgsql/bin/postgres --single -D /var/lib/pgsql/data postgres"

backend> VACUUM

However, this doesn't seem to help - I receive lots and lots of messages like this:

<2008-03-21 21:43:27 CET - 11845: @>WARNUNG: Datenbank »postgres« muss innerhalb von 4294805194 Transaktionen gevacuumt werden
<2008-03-21 21:43:27 CET - 11845: @>TIPP: Um ein Abschalten der Datenbank zu vermeiden, führen Sie in »postgres« ein VACUUM über die komplette Datenbank aus.

i.e. "database 'postgres' must be vacuumed within 4294805194 transactions."

That's what I just did, but the problem persists. Whenever I issue a 'vacuum', the number of transactions simply decreases.

This is PostgreSQL 8.2.4 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)

I am absolutely lost about what to do now - and it's a puzzle how this could have happened in the first place. I have configured autovaccum AND I run a vacuum verbose analyze over all databases every single night. What do I do now? Is there some alternative to reinit and going back to the last dump?

Urgent help would be very much appreciated.

Kind regards

Markus

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