The OUI threw the subject error during installation of Grid Infrastructure 18.104.22.168 on OEL 6.4 with Job Role Separation. This occurred after successfully running root.sh when the OUI started the NETCA task . The solution was very simple: go to /u01/app/12.1.0 and "chmod g+w grid". At that point I was able to click "retry" and it worked perfectly. There were no other errors or issues during the entire installation.