This happened on my new cpanel box.
Any idea why and how to resolve it?

Also after I restart it and I type ps -aux | grep named show the following result:
named 8569 0.0 1.0 13080 5084 ? S 10:43 0:00 named -u named
named 11767 0.0 1.0 13080 5084 ? S 10:43 0:00 named -u named
named 26855 0.0 1.0 13080 5084 ? S 10:43 0:00 named -u named
named 29749 0.0 1.0 13080 5084 ? S 10:43 0:00 named -u named
named 28015 0.0 1.0 13080 5084 ? S 10:43 0:00 named -u named

there's 4 four named process. Is it normal??

Yes that is normal, by default it fires up that many. As far as why it is stopping you need to check you bind log files. I believe by default the errors are logged to /var/log/messages and see if it has some information on why it has stopped. Then go from there to find a solution.

Hope this helps,
Mike