Modern fridges have an auto defrost feature - every now and again they stop cooling and have a burst of heat to melt any ice that's built up. The ice melts and should run out of a drain hole at the back to evaporate naturally in the air of the room.
When the drain hole gets blocked the water can't run out - it messes the inside of the fridge.
Find your drain hole and poke it clear.
Peccavi, March 2010
