pg_dump - lost synchronization with server: got message type "d", length 6036499

Can someone shed some light on what's happening here?

D:\backups>pg_dump -Z 9 -Fc -C -U postgres -f sheepcrc\dbback.dmp sheepcrc2
pg_dump: Dumping the contents of table "uploadeddatafiles" failed:
PQgetCopyData
() failed.
pg_dump: Error message from server: lost synchronization with server:
got messag
e type "d", length 6036499
pg_dump: The command was: COPY public.uploadeddatafiles (id, username,
projectid
, aspsession, filename, filetype, filesize, filedata, uploadedon,
"timestamp") T
O stdout;

pg 8.3.1 server on w2k3
pg_dump 8.3.1 and 8.3.3 on the same machine both do the same thing.

data directory and backup directory excluded from virus scanner.

The followinng variations also failed. The length seems to be either
6036499 or 8435588 (84... is most common).
pg_dump -Z 9 -Fp -C -U postgres -f sheepcrc\dbback.dmp sheepcrc2
pg_dump -Fp -C -U postgres -f sheepcrc\dbback.dmp sheepcrc2

uploadeddatafiles holds excel spreadsheets in the filedata column.

sheepcrc2=# select count(*) from uploadeddatafiles;
count
-------
405
(1 row)

sheepcrc2=# select sum(length(filedata)) from uploadeddatafiles;
sum
-----------
271067619
(1 row)

This completes and returns all rows
select id, md5(filedata) from uploadeddatafiles

klint.

--
Klint Gore
Database Manager
Sheep CRC
A.G.B.U.
University of New England
Armidale NSW 2350

Ph: 02 6773 3789
Fax: 02 6773 3266
EMail: kgore4(at)une(dot)edu(dot)au