In Redhat from V5.2 up to Beta7.0 I foudn a bug in the userdel script..

Example:

I added a user named user1, adduser added them to /etc/passwd, /etc/shadow
and /etc/groups.  usualy creating and adding them to group named user1..
If this group already exists it will make a duplicate group entry.  When
you try to userdel
this account with the duplicate group entries userdel will hang, using
strace on this showed
it stuck in a loop loggin to /var/log/messages, the message in
/var/log/messages would
repeat deleting group user1..

Basicly userdel needs to be smart enough not to choke if there are 2
entries for a group in the groups file.. and adduser needs to be smart
enough not to add it a second time if it allready exists.

-Steve