If your looping is showing up on the bottom of the fabric, then the problem is your top thread. Take the thread off and completely re-thread. Make sure nothing is impeding the thread as it travels through the machine (on my machine, often times the upper thread gets hung up on the carry handle). After you've done that, if you still get loops on the bottom, try adjusting your top tension or possibly switching thread.
Your bobbin thread should not be loose. Do this test - thread the bobbin as you normally would, then holding the thread, let go of the bobbin. It should drop about 6 inches and then stop. If it drops all the way, tighten the screw. If it doesn't drop at all, loosen the screw.
Hope this helps. I'm sure others will have valuable suggestions as well.