You might want to look into getting some Olympic shoes instead of using your regular running shoes. The Nike Romaleos II are great and will help with your form and will prevent injuries to your ankles.
Also, try to make sure you are using the correct type of bar that has at least a 10 needle point ball bearings. The bar should spin easily when you spin it. If you're just using the typical crappy bars that come in most gyms the weights will turn when you lift them and can torque your shoulders, especially on power snatches.