People were telling you that your machine is attempting to authenticate using yp, because it is still in the authentication configuration. And, that even though you stopped a yp service, it may have come back after a reboot, unless you stopped it from starting.,

Make sure the yp services do not start on boot( that was editing th rc files, and also, the easier way on redhat anyway "chkconfig ypserv off" as owensleftfoot said).

Make sure that your machine does not try to use NIS for authentication( authconfig).

You need to run authconfig as root, and unselect anything which mentions NIS, then run

chkconfig --list

and look through it to find all of the NIS related services which are scheduled to start in runlevel 5 or 3,

and then run

chkconfig <servicename> off

for each of them, I think the following are the NIS services you will need to turn off

chkconfig ypserv off
chkconfig ypbind off <----------------- I think this one, along with autconfig change, solves problem.
chkconfig yppasswd off

You can also turn off portmap unless you are using nfs...

chkconfig portmap off