My machine is locking and apparently tangling up inside of the bobin case

Here's whats going on. I am currently sewing up a cloak made from fleece and faux leather (upholstry variety). I bought a new thread to try out for tougher use and I bought new bobins and that was all I a decided to do differently this time as oposed to all other times I have used this blinking machine. I try to sew a simple seam, just a loooooooong straight line, and I still have problems. These problems manifest themselves as the machine coming to a violent and sudden stop and refusing to advance further. The needle will go up and down, but the fabric will not advance. When I try to remove the fabric I discover that it has been stuck to the machine and have to cut it loose from below with an exacto blade. I then open the bobin case to figure out why there are now several threads coming from it rather than just one and find that those several threads are severed, but on the bobin. As though the bobin had loosened up enough for somebody to make a cut and sever several loops of thread while it was still on the bobin. I clear out the loose threads, re-thread the machine, and move on. It happens apparently randomly too - I will go several passes with no problem, and then lock the machine every 15 freaking stitches. In its earlier incarnation I also had irregular stitches, they kinda looked like this --------u----u--u------u-----u---- it wasnt a scary tangle like I have dealt with before, just odd. I have tried: ALL tension settings from lowest to highest with no effect adjusting stitch length blowing half a can of air through the bobin case and related parts (the machine has been recently serivced in terms of time between use so shouldnt need oiling or anything yet) varying the speed at which I actualy sew the seams changing the bobin out for a different one flipping the thread spool up-side-down (its one of those speels that has a very distinctive bottom, but if you put it right side up the thread pulls from the oposite side that the machine threading instructions wants it to) adding the second spool holder and diverting the thread past that to help keep things from goin' nuts (when it locks, the machine has clearly pulled too much thread and it drapes down from the spool) and at times it loops itself around one of the threading elements a second time as well. so. . . any ideas?