I had an original academic installation of MATLAB 2018a on my laptop which worked fine. Later I added a 2018b version as well. Both worked fine. But, recenltly on a random day, the laptop crashed while MATLAB 2018b was open. Ever since then, MATLAB 2018b executable does not open MATLAB, as if it does not exist at all. I reinstalled it fresh, but that did not help. The 2018a version opens and works randomly, but again also randomly freezes forever to do such simple tasks as 2+2. Any help is greatly appreciated.