Problems restoring a DB with oids

Hello,

I have two servers running postgres 7.3 (Server Jupiter), and 7.4.3 (Sever
Saturn), in my office. I have a master database in Jupiter, that contains
a DB with images, OIDs (lo type).

I'm trying to backup the database from Jupiter and restore it in Saturn.

I do this, from Saturn:

pg_dump -Ft -b -U dbuser -h saturn dbsample > db.tar

Then, I create the user and database in Saturno, and perform this:

pg_restore -Ft -v db.tar -d dbsample -U dbuser

But, pg_restore stops, showing this message:

pg_restore: no OID type columns in table photos1
pg_restore: fixing up large-object cross-reference for "inventory"
pg_restore: no OID type columns in table inventory
pg_restore: fixing up large-object cross-reference for "photos2"
pg_restore: fixing large object cross-references for photos2.photo
pg_restore: fixing up large-object cross-reference for "parts"
pg_restore: fixing large object cross-references for parts.qltymemdoc
pg_restore: [archiver (db)] error while updating column "qltymemdoc" of
table "parts": ERROR: large object 609937 does not exist
pg_restore: *** aborted because of error

But this large object, exists. I "untar" the "db.tar" file, and there is
a file called "blob_609937.dat", and it appears in the file "blobs.toc".

Where is the problem ?
How can I do a safety reliable backup in postgres, with databases that contains
"lo" columns ?

I have tried with diferents options (dumping and restoring), but always
appear the same problem. This have seen this problem in databases using
large objects (lo type), since version 7.3.

It is a critical situation, because I have seen those problems in a production
system, .... what will happend if the database would crack ?

Thanks.