Shawdow passwords only half there

[Paul Waldo <pwaldo sysnet net>]

Hi all,

I am running Red Hat 5.2 with shadow passwords installed.  I have run
the password and group conversion utilities, so I know have the files
/etc/shadow and /etc/gshadow
I manually set the /etc/passwd and /etc/group file's permission to 600. 
Most things work now.  For example I can log on (which is a good thing
:-)  But other things are broken, for example:

[I have no name! delphi /etc]$ whoami
whoami: cannot find username for UID 500

I have run strace on the whoami command and found that it is trying to
look at /etc/passwd.  Is there something else that I need to do to get
shadow passwords working fully?  TIA

Paul