Error when editing virtual host

Hi, I have been using Cloudmin for quite a while without any problem. I recently recently tried to edit one of my old-runing virtual host and got this unexpected error:

Failed to save system details : The new hostname myhost.cloudmin.my.net cannot be resolved to an IP address

I made further tests and realized that the same error is generated for all my virtual hosts. Apart from this all works fine.

I run Cloudmin 1.740 on an Ubuntu 12.04 Server host.

I suspect the issue is with Bind, but I have not been able to correct.

Any hint will be highly appreciated

George