When i finished installation the Redhat Enterprise Linux 6.2, and login to the system, I can't login although username: root and Password correct. I install on the Hp Blade Server. I don't know why.
How to fix this error? who can help me? 
Thanks!
Are you trying to login on the console or via ssh?
yes, i am. But i can't until login in the system. Thanks!
Again, do you login on the console OR via ssh?
If you try to login via ssh, then it's clear. root is not allowed to login via ssh by default for security reasons.