HELP in Porting Versions

I'm trying to port my 6.3.2 to a 6.4.2. I've done a pg_dump myDB > out.sql
and then do a psql mynewDB -e < out.sql . I've also tried a \i out.sql in
the psql command line.
I've got the following message after a while. The schema and all were built
and while populating the DB, I've found that this happened after inserting a
few records.

pqReadData() -- backend closed the channel unexpectedly.
This probably means the backend terminated abnormally before or
while pr
ocessing the request.
We have lost the connection to the backend, so further processing is
impossible.
Terminating.

Any ideas?

Thanks