Thread gets caught in the bobbin area all the time on these babies. It only takes a quarter inch of thread to put them at a standstill. What most often causes the problem is trying to remove the work with the take up lever NOT being all the way up.
So, make sure your machine is properly threaded (needle threads from right to left) and make sure the take up lever is in the 'full upright position' before starting or stopping sewing.