I just received a 35mm f/1.8 DX lens for my Nikon D50 for Christmas, and took some shots where the lights on the tree were the main source of illumination. Almost all of them exhibit very prominent green after-images of the tree lights. For example, in this image they run from the left side of the mirror down to the left side of the fireplace:
Are these artifacts caused by the lens, the camera, the filter (a Tiffen 52mm UV protector), or a combination of them? How can I avoid them in future shots?