Hi Peter, my ST3 wont open now only the Beta works. I will try reinstalling it and reloading my current backup to se if it comes to life.
I have just reinstallled ST3 and resored my latest full backup i am up and running again, i suspect this has something to do with plugin effects.
Yes, you most likely uninstalled a plugin that was inserted as a master effect. That bug exists since adding AUv3 effects a year ago.