Help! I just moved in to an apartment and the freezer smells horrible! Any ideas?

When I first got into the apartment, I thought that maybe the smell was from the previous tenants or something - and then I checked the stove - it smells like the gas is on or something, it's a nauseating/sweet/propane smell - well, it's coming from the freezer! It made the ice cubes taste horrible, and all of the liquids in the fridge are absorbing the smell. Does anyone have any ideas what it could be?