Modern fridges and freezes have an auto defrost feature - when you open the door warm air from the house enters and the moisture in the air condenses out on the cooling plate(s) and turns into beads of ice.
To stop the ice building up every now and again a short burst of heating melts the ice and the resulting water runs out through a tiny drain hole.
If the drain hole is blocked with crud then the water forms a pool at the bottom and runs out when the door is opened.
I suspect your hole is blocked.
http://www.appliancerepair.net/refrigerator-repair-6.html
Peccavi, May 2013
