Error Migrating From 7.4 to 8.2.5

I am running PGSQL 7.4 on a Solaris 9 system. I am trying to upgrade to
8.2.5. Both 7.4 and 8.2.5 are on the same server. When I try to use 8.2.5
pg_dumpall to dump the 7.4 databse I receive the following error:
pg_dumpall: query failed: ERROR: xlog flush request 58/A0AFB0C0 is not
satisfied --- flushed only to 5/B2004628
CONTEXT: writing block 15 of relation 21182403/16408
pg_dumpall: query was: SELECT usename as rolname, usesuper as rolsuper,
true as rolinherit, usesuper as rolcreaterole, usecreatedb as rolcreatedb,
usecatupd as rolcatupdate, true as rolcanlogin, -1 as rolconnlimit, passwd
as rolpassword, valuntil as rolvaliduntil, null as rolcomment FROM
pg_shadow UNION ALL SELECT groname as rolname, false as rolsuper, true as
rolinherit, false as rolcreaterole, false as rolcreatedb, false as
rolcatupdate, false as rolcanlogin, -1 as rolconnlimit, null::text as
rolpassword, null::abstime as rolvaliduntil, null as rolcomment FROM
pg_group WHERE NOT EXISTS (SELECT 1 FROM pg_shadow WHERE usename =
groname) ORDER BY 1

I shut down the 7.4 database and ran pg_resetxlog. This is just a test so
I am not worried about losing data. Restarted the database and tried
pg_dumpall again. I still received the same error but on a different
block. How do I fix this problem? Thank you.