• by David Goetzl  @dgoetzl, May 6, 2011

Christina Norman, the former MTV Networks executive who led the launch of OWN: Oprah Winfrey Network, has left her post as CEO just four months after the network went on the air. Discovery Communications COO Peter Liguori, who was involved in the network's launch process, will take on Norman's role on an interim basis, while keeping his Discovery role.

Ratings have not been stellar at OWN, despite a significant investment by co-owners Discovery and Winfrey's production entity Harpo. The joint venture also includes Oprah.com.

Norman was a highly successful executive at Viacom, having led both MTV and VH1.

"Joining OWN was a great opportunity, and launching it successfully and drawing more than 67 million viewers is one of my proudest achievements," Norman stated.

OWN, which is in more than 80 million homes, will be launching a Rosie O'Donnell talk show in the fall and "Oprah's Next Chapter" in 2012.

Winfrey, citing Norman's "incredible passion and many sacrifices in helping to launch the network," stated that she plans to be more involved. "With the final taping of 'The Oprah Winfrey Show' only a few weeks away, I will soon be able to devote my full energies to OWN. This is a natural point of transition, and I am confident that Peter, as an integral part of the launch of OWN, will be a terrific partner for me going forward."

Liguori oversees Discovery's interests in OWN, The Hub and 3Net, along with other roles. He had been entertainment chief at the Fox network.