Matlab is no-response when I use NSGA-II code to run my optimisation program.

http://www.mathworks.com/matlabcentral/fileexchange/31166-ngpm-a-nsga-ii-program-in-matlab-v1-4 This is the optimisation program what I used for my program.I want to solve a Multi-objective design optimisation of bearings problems. But with the generations increased,the program become a little slow and became no-reply in the end.It's ofen occured after the two or three generations finished(my optimisation program is larged and there are nonlinear equations should be sloved by Newton-raphson method in each populations.) When matlab become no response,I must shut down it and ctrl+c can not work.It's always occured in my objective function evaluating progress.I check my memory, It's up to 6-7GB when the program running, my computer memory is 16GB so that's OK.but it's stranged that when the program will become no-response is totally random. Could anybody give me a adive?Forget to say,I used lots of symbolic computation in my Objective function,it's diffcult to avoid.