Vacuum returns error

PG 7.2 and RH 7.2

Developer dropped ~30+ tables from 4 different DBs on the same
server.  Queiries began to fail: unable to locate file;
/var/lib/pgsql/pg_clog/0006.

Immediately VACUUMed DBs.  Queiries began returning OK.

Minutes later vacuumdb -z DB_1, returned OK.

Attempted vacuumdb -z DB_2, failed with error similar to above.

Where can I locate more comprehensive error message
information?  Any recommendations would be greatly appreciated.

Thanks

- Bill