[CentOS] error when logging into system

Hello everyone,

I have a CentOS 5 system. On this system, I used the usermod -n and
groupmod -g to change the user id and the group id for a standard,
regular user from 500 to 1000.

I then ran the following commands (as root), to make sure all the
files were changed to match:
find / -uid 500 -exec chown 1000 {} \;
  -- and --
find / -gid 500 -exec chgrp 1000 {} \;

Now, whenever I try to login as that regular user, I get the following error:
id: can't find name for groupd ID 500

I have checked /etc/passwd and /etc/group and both files are correctly
showing 1000 as the user and group ids. I didn't see the id isn't
listed in either of the shadow files. All of the files in the user's
home directory have the ownership and group set to id 1000.

I have rebooted the system to make sure nothing was being stored in
memory, with the same results.

Any other thoughts to look into to correct this error?
-- 
Doug

Registered Linux User #285548 (http://counter.li.org)
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Never trust a computer you can't throw out a window.
   -- Steve Wozniak