Upgrade problem, with GRANT

Well, since I am posting I might as well ask two questions..

FIrst, when I upgraded from 6.2.1 to 6.3.2 I performed a pg_dumpall and
after I did an import of the db.out.. All seemed okay, and I assumed
that permissions were okay, but I was wrong.
I was able to log in under postgres user, and the data seemed fine, but
there were no GRANTS
THEN I tried to GRANT all on table_name to user_name;
but it kept coming up as nonexistent user.. It worked fine before the
upgrade, and the user_name does indeed exist..
What is the problem?

Quick reply would be handy as it is a production databse..

Also, I noticed that float8 and horology, (as well as geometry) failed
on a Pentium 100 with Linux 2.0.34.. is that normal, and what is
horology? SHould I worry? The diff command didn't reveal much on the
horology.out