I updated the MySQLi server behaviors extension to address the issue with Authenticate User. If you re-install that should be resolved.
I'm unable to reproduce the crash when running Security Assist. Is there an error when it crashes? What page does it crash on?
I may need to set up a screen sharing session to debug that issue with you since I can't reproduce it locally. Please post back with a good US phone number or Skype contact information and I can set up a call to debug and find a resolution with you directly.