OpenVPN with Witopia periodically fails to resolve DNS for server

[BeepStein]

I am using the openvpn client with a vpn service Witopia. The client at some point in time is failing to resolve the DNS name of the server.  It works when i restart the client and/or reboot the pfsense.  I do not know what is causing it.

It makes a successful connection. But at some point in the future i see errors in the VPN logs stating it can't resolve the DNS name.

Any thoughts?