problems updating table

Howdy:

Running PostgrSQL 7.2.1 on RedHat Linux 7.2.

I'm trying to update a table and I'm getting permission
denied from what seems to be a totally unrelated
table.

I am logged on as the table owner and I'm getting this
message:

[snip error]

test=> \dt sys_users
List of relations
Name | Type | Owner
-----------+-------+-------
sys_users | table | web
(1 row)

test=> \dp sys_users
Access privileges for database "bcn"
Table | Access privileges
-----------+----------------------------------------------------
sys_users | {=r,web=arwdRxt,hmp=arwdRxt,"group staff=arwdRxt"}

test=> \c test web
You are now connected to database bcn as user web.

test=> update sys_users set "username"='MARISSA' where "username"='marissa';
ERROR: hmp_mbrhlth: Permission denied.

test=> \dt hmp_mbrhlth
List of relations
Name | Type | Owner
-------------+-------+-------
hmp_mbrhlth | table | hmp

[/snip error]

I've done this before and I believe I'm using the correct
syntax. I've even tried to get brave and do it as 'postgres'
and I still have errors.

What am I missing?

Thanks!

-X