I've had the same problem. Some guys on another helproom are saying the problem can be fixed by updating to the latest version of your Nvidia display driver. However, that didn't work for me. I fixed the problem (for the time being) by reinstalling an older version of Skype - V18.104.22.168. I think I will check for the latest version of Skype sometime in Nov-2007 to see if Skype has finally got around to fixing the problem by then.