Ive been having the same problem for a few weeks now and tried taking it apart and cleaning the lines, sometimes it would work and then it would stop working again, we were just about to give up on it and buy a new one until i had one more look inside the freezer and found what appears to be a reset switch and i think its solved my problem, if you have a look under the temperature control panel you will see three plastic screw caps, two small one big, remove the big one and insert with a small screw driver or mains tester, turn clock wise until you hear it click and the fridge should start up again.
Mark
February 2011