10.50b2 is coming soon, which should fix the issues with the various plugins crashing the sim (bugs that were introduced in 10.50b1). Until then, I recommend going back to 10.45 (or temporarily removing your plugins and attempting to run that way).
EDIT: Sorry, I was mistaken. Per this developer blog post, we're aware of the issue with plugins crashing the sim, but we don't know when we'll have a fix. If you can get me the Apple crash report in addition to the Log.txt file, I'll be happy to forward it on to the development team.