I have the same fridge and had the same problem. I had a service man come out and he had to empty all my food out of the freezer side take the back panel off of the inside of the freezer and take a hair dryer to thaw out all the frozen ice inside the panel have towels on hand. Then he replaced the defrost heater which keeps the inside of the panel from freezing. He did this about 11 months ago and now I am having the same problem again. Good luck, pretty easy fix i'm now trying to find the defrost heater online so I can do myself he charged me $170 for the repair where you can probably get the part for around $20. Hope this is helpful.
John H
May 2007