Hi all. I have owned a d300s for a few months now and used it fairly extensively. Only recently though have I used the continuous focus function. First thing I noticed after using continuous focus flat out that it stopped focusing after 10 minutes or so of use. I had to turn the camera off for a few seconds turn it back to single servo and then switch back to continuous. I thought it may have been my lens (120 - 400m sigma) however I switched to another lens and the same thing happened. Secondly I notice that when i switch my camera on when it is in continuous focusing mode that it makes a squeeking noise. When I turn the camera on in single servo mode the squeeking noise is not present. My questions is, is this a problem with this camera or may it be a faulty item. Any input is appreciated.