I am getting the same issue. I have switched from using Windows to a Mac and have the latest build (Dw 2015, build 7884).
The Windows version doesn't do this, however my issue is pretty much the same as Mike's...I can use it a few times and then all of a sudden the app just quits and I get the OSX report coming up and asking me to Reopen Dw.
I logged in yesterday to make sure that I have the latest version of MySQLi and I have.
Did you manage to fix this for Mike?
PS: If you want the log that OSX throws up let me know.