problem with pg_dump

Hi all,
We are using pg as db for many erp installations.
In general it is working great.
But at the monet I have problem (I think it is database corrupted, but I
am not sure) by running pg_dump.
I receive this message:
pg_dump acc01 > dmpacc01
pg_dump: query to obtain list of data types failed: ERROR: More than
one tuple returned by a subselect used as an expression.

I can not find nothink wong in my log-file. The lastest records are:

LOG: shutting down
LOG: database system is shut down
LOG: database system was shut down at 2004-06-13 09:39:03 EEST
LOG: checkpoint record is at 3/313382E4
LOG: redo record is at 3/313382E4; undo record is at 0/0; shutdown TRUE
LOG: next transaction id: 4046855; next oid: 958527775
LOG: database system is ready
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
WARNING: ROLLBACK: no transaction in progress
ERROR: More than one tuple returned by a subselect used as an expression.

We are using pg 7.3.4 for this install (we will upgrade to 7.4.x soon).

Pls. help me to sort out this problem. It is production db and is
important to resolve the problem.
regards,
ivan.