I contacted tech support on this issue yesterday and have an open case in regard to the 936L motion detection problem. I have three of these cameras that are constantly re-focusing and triggering the motion detection. Mine don't have anything to do with clouds or movement of the sun. It is simply a small refocus of the pixels that triggers a motion alert. I have tried to put them on night vision and while that helped a slight bit, I still get 90% of the false detections that I was getting under the normal day view.
Two of my cameras are located outside and are protected underneath the eve's of the house. So I don't have a situation where it is pointing out a window. The IR night vision won't work anyway if you point it out a window. I also have one in the living room and it has the same pixelating issues that the other cameras have (and it is a room that gets no direct sunlight).
I have a fully functioning DCS-2630 that has zero issues with motion detection and works perfectly. This leads me to believe it is an issue with the 936L as all three of mine have this issue, even when adjusting the sensitivity down below 10% (which then creates a situation where the camera does not detect actual motion of a person when the get near it). I asked to tech support to expedite this and get a firmware update out ASAP.
You mentioned that yours is workable in the short term, but in my opinion putting the camera away from all windows, not aimed outdoors, set to IR mode only, and turning off the email notifications essentially makes it unusable as a practical security measure and requires and immediate firmware fix from D-Link.
I do appreciate all your help FurryNutz, it is very nice of you to try and recreate these issues and help us out. I would have been much more aggressive getting this fixed a month ago when I purchased the cameras, however I had a bigger issue regarding playback that took D-link support a month to figure out. If you have a special character in the password of the camera it would not play back the clips on an iOS phone or tablet.
So I had two major issues with these cameras and have just recently got the 1st one fixed. Need this motion stuff repaired now as well. This can't be isolated to just a few users judging by the same problem with all my cameras. I also took two back to Best Buy when I originally purchased because they had the same issue. So I have five of the 936L's that all do the same thing.
Should D-link solve this problem, the 936L is will be a solid option for an economical security setup in the home.