If it is a front wheel drive car having good tires on the front and shitty tires in the back is the most likely cause. Having said that, if your rear brakes are worn down too far or are out of adjustment then this could also be a cause. Lastly, you may just be too inexperienced in driving with poor road conditions. With years of experience driving many types of vehicles in all weather and road conditions it is my experience that when you hit ice the only thing you should do is steer because accelerating or braking causes your tires to break loose and start sliding. Your brake system is designed so that the majority of the stopping power is in the front end. So applying the brakes (even lightly) applies a greater force in the front. Remember to feather the brakes when you must use them in slippery roads conditions.
