clog problem

I've got this:

FATAL 2:  open of /usr/local/pgsql/data/pg_clog/02B6 failed: No such file
or directory
server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
connection to server was lost

This was when the nightly vacuum was running.

I had this problem a few weeks ago and had to restore from a backup. Whats
is causing this? I've seen some refs. to clog problems relating to
7.2.beta somethin, but not found any resoloution.

Cheers,

Bob

Bob Parkinson
rwp@biome.ac.uk
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