[G4] trouble setting up user accounts

[vwmai]

Hi,

I am having issues setting up user accounts on my G4/500 running OS  
10.4.7. Setting up the account and password goes OK. When I log out  
and try to log in as a different user (entering the correct password)  
the login window shakes as though the username and password are  
invalid. I have tried setting up several different accounts and  
double checked the passwords and no deal. I have tried doing the same  
thing on my G3 iBook which also runs OS 10.4.7 and it works without a  
hitch. I am stumped. Any ideas?

Thanks
Chris