REPOST:Memory Allocation error using pg_dump on 7.4

I repeatedly get this error whenever I try to backup a database

The command used is:

pg_dump -Fc -O -U username tablename > tablename.20060122

pg_dump: ERROR: invalid memory alloc request size 4294967290
pg_dump: SQL command to dump the contents of table "cc_ratecard" failed:
PQendcopy() failed.
pg_dump: Error message from server: ERROR: invalid memory alloc request size
4294967290
pg_dump: The command was: COPY public.tablename(id, ...

Is there a bug somewhere in there?

Is there something which needs doing in regard to my memory allocation settings?

The table involved is one of the larger tables, but at only 400,000 records it
shouldn't be a problem

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