Need to find a common connection with all the times it has crashed. What were you doing at the time? What do all those instances have in common? Have you been using the same plugins each time?
Do you get any messages at all, or does the computer freeze up? BSOD? or does Cubase just crash to windows etc etc.
Also, check your Synchrosoft License Control software and make sure you have the latest version. That had me baffled for hours once.