problem with upgrading 7.2 -> 7.3.4

Hello;

With your help I've got a recently installed postgres7.3.4 version. But when
I try to upgrade my data I have an error.
I've spent a couple of hour trying to solve it with no result, and perhaps
you can help.

I've got two different computer one with the 7.2 and the other with 7.3.4
version.
I've made the dump_all with no problem. But when I type, in the new psql:

./psql -d template1 -f dumpall.backup.26-08-2003
I obtain the messages:
----------------
You are now conected to database template1
DELETE 3
CREATE USER
...
CREATE GROUP
ERROR: user "javier"does not exist
ALTER GROUP
...
\connect: FATAL user "javier" does not exist
-------------------
I've also tried (seen in Administrator guide 9.3):
./psql template1 < dumpall.backup.26-08-2003
what I guess is the same. Because I obtain the same messages.

And I obtain the messages no matter if the groups or user "javier" (me)
existed previously in the new postgres cluster (I've tried to CREATE, DROP,
re-CREATE... "javier" before bringing the dumped file with the same result).

Can you give me any clue?

Thanks,

Javier