Unable to pg_dump 8.1.2 - memory alloc error

Hello

I get the following error when dumping a pg database with WIN_1252 encoding:

pg_dump --clean --no-owner dumpfile | gzip >/home/postgres/globalen.dump.gz 2>>./err.out

pg_dump: ERROR:  invalid memory alloc request size 4294967293
pg_dump: SQL command to dump the contents of table "site" failed: PQendcopy() failed.
pg_dump: Error message from server: ERROR:  invalid memory alloc request size 4294967293
pg_dump: The command was: COPY public.site (site_id, url, status, created, "domain", title) TO stdout;

Possibly related is a particular query with pgAdmin on same site table with above error yields
ERROR:  invalid multibyte character for locale

I have upgraded from 8.1.2 to 8.1.6 but get the same error.

Any help appreciated.

Regards,
David.