Hi,
Are you using Extenal LDAP Directory or internal user store on EEM?, open userstore configuration on EEM to view verify.
Try using pamadmin to login, user (pamadmin) and password (pamadmin) all lower case.
search users on EEM manage identities, see if you can find the users that cannot login.
login to your EEM server, verify that the EEM services (CA iTechnology iGaeway and CA Directory - itechpoz) are up and running.
Thanks
Sivuyile