I had the same problem: Tech Support gave me this response and it worked. The funny thing is that once every plugin had been moved and then copied back in, S1 didn't crash. So I never found a problem plugin, but the process must have fixed something so now its ok.
Here's the solution that worked:...
Please go to Macintosh HD\Library\Audio\Plug-ins\VST, VST3, and Components.
Copy the contents of these folders to respective folders on your desktop so that the original folders are empty.
Open S1 and test for the issue again. Add your plug-ins back to the respective folders a few at a time until you can identify the one that is causing the crash. You will then want to contact the manufacturer of the plug-in for information about compatibility, updates, and known issues.