I've just ran a MSFT update and now Simplified 3D won't stay open. It starts, opens for 2-3sec, then closes without warning!? I've uninstalled, installed, rebooted... still lights out for Simplified
When the software opens, it usually tries to reload your saved settings and models from the last session. If the microsoft update somehow tampered with those settings it might be what's causing the problem.
One easy idea could be to try temporarily removing the savedState.factory file from the directory below:
C:/Users/%USERNAME%/AppData/Local/Simplify3D/S3D-Software-V5
That will prevent the software from loading the prior session temporarily to see if the software opens successfully.
Note that you may need to enable viewing of hidden files and directories to browse to that location in the file explorer.