MAC - Cannot stop me appearing permanently offline to a contact?

[[email protected]]

To half of my contacts I cannot appear permanently offline, to the other half I cannot stop appearing permanently offline. The menus have no effect. I have deleted and reinstalled, deleted preferences and done everything I can think of to solve the problem. I have read that there can be an issue with Yahoo DNS not responding, I have flushed my DNS settings.

Any advice? will it clear itself up?