If you want to diagnose what is happening you can start by suppressing all your applied loads and see if it will run. Then suppress all but one and try running and see how it behaves. Walk through all your loads until you find the one causing the issue. Once you have found it, reduce your applied forces down to something really low, like 1 Newton and see what happens. Do the same with your constraints, simplifying things by using fixed constraints instead of more complicated ones to try and narrow down the source. This process will help you understand what loading or constraints are the source of your problem.