I run simulations, some of which take on the order of 90 minutes. If I get one started and walk away to do other things, I find upon returning that the screen is dark and computation has stopped after 30 minutes or so. If I then click on the mouse and get the screen to come back, the simulation continues. I am using Windows 7 Professional on an HP laptop with an Intel I7 processor and 16 Gigs of memory. Is there a way to keep the computer running when I am not present? I am using R2015b. Thanks.