Full Computer..... Havent put ANYTHING on it !?!?

My Other computer has recently started giving me messages saying that it has less than 2mb of space left on c. This is really strange becasue i dont have any doccuments on it (they are stored on another computer and “My Doccuments” folder is linked to that netword folder). c:/WINDOWS is also appearing to have 34.9gb in it, when it should have less than 3. Does anyone know what could be going on?