Database corruption

Hello all,

Whilst running a regular pg_dumpall, I received the
following error from our spamassassin DB.

pg_dump: ERROR:  could not access status of transaction
4521992
DETAIL:  could not open file "pg_clog/0004": No such file
or directory
pg_dump: SQL command to dump the contents of table
"bayes_token" failed: PQendcopy() failed.
pg_dump: Error message from server: ERROR:  could not
access status of transaction 4521992
DETAIL:  could not open file "pg_clog/0004": No such file
or directory
pg_dump: The command was: COPY public.bayes_token (id,
token, spam_count, ham_count, atime) TO stdout;
pg_dumpall: pg_dump failed on database "spamassassin",
exiting

It's clear something's amiss with the database but I'm not
sure where to go from here.  Is any data from bayes_token
recoverable, should I just delete the data in that table or
does the whole database need to be dropped and recreated?

Tia,
Shane

--
http://www.cm.nu/~shane/