@sticksandstones -- I took my 50mm to the camera shop where I had purchased the lens and they sent it to Canon to be repaired. I'm hoping it's not too expensive :( but I can't imagine not having my 50mm be unreliable for any longer.
@amandal -- thanks for agreeing with my assessment on the mood . . . I chose this one specifically for the feeling of nighttime activities and the ambience they project.