JavaLawyer,
It's been over a week and D-Link did not get back to me. This is consistent with my past experiences with them. They either don't respond at all or they send a pre-formulated response, usually saying to reset the firmware. I have had the camera for 6 months--so it was absolutely still under warranty.
I found the sliding filter shuttle was getting caught halfway, so I disassembled the camera, removed the filter assembly, and took it apart. There are two solenoids, one at each end, wired together to pull the shuttle left and right depending on the polarity. There are two small magnets, one on either end of the shuttle. The solenoid is energized for only a fraction of a second, so any impediment to movement will cause the shuttle to stop mid-way, where it is difficult for the solenoid to grab it. A firm tap on the side of the camera can free it, but there is basically no margin for any kind of friction in there.
The magnets and glass pieces (one clear, one blue tinted to filter IR) are all attached to the plastic shuttle frame with small globs of silicone. If you attempt to clean the camera from the outside using a Q-tip, you will pop the glass pieces off the frame and the whole assembly will get stuck. In my case, the plastic shuttle frame was warped ever so slightly and creating friction. I removed the glass pieces and magnets, cleaned everything, straightened the plastic shuttle, and reattached the components with extremely small drops of superglue applied with a very fine point. (I cut a sliver off an old credit card.)
I'm sure the warranty is beyond void at this point, but with tiny screwdrivers and ample patience, it took maybe 2 hours to fix.