Hi, have been plagued by this problem for 2 years... and genius has just granted me the answer. You need to delete the solver, you cant do this from a button..so. Go to the Simulation tab on the cloth tab bar, then look at solvers, there should be a list of solvers you've created. Remember the name of the solver(s) and open the script editor and type in: "delete solverName" without the speach brackets, solver name should be something like cpSolver1, then CTRL+ENTER to execute that command, now you should be able to save ok.