I have (had) the same problem with my Sub Zero, and now there is no ice on the wall but the refrigerator is leaking. I just looked to see if the bottom drain was clogged but there's no drain, only a flex-tube going through a grommet. There is no water below the vegetable bins - dry as a bone. This started after a 2-week power outage (Hurricane Gustav) and then a thorough cleaning. At first there was ice - so I turned the setting down, but the the leaking began.