Cycles rendering glitch, some frames appear without lighting

When I render in cycles, I sometimes get frames that appear as the one shown. The scene is well lit, but about 8% of the frames glitch like the one shown. I have not been able to find a solution so far, so any help would be much appreciated!

How is anyone supposed to help you?
No blend file, no image of the correct render to compare to (at least give an idea of what you did expect to see, I do like the purple and black personally), no specs on harwdware, os or version of blender, no screens that show any other pertinent information of your workflow. Blender Internal or Cylces? Rendering to image sequence or video? Are you using skype while rendering?..
Maybe this question belongs in the psychic subsection of the forum.