So after one more battery-pull reboot of the phone, I went out to the Z yesterday to collect some firmware information anticipating a call to the dealer today.
Everything is now back to normal.
I don't know what to think, but as we are VERY near the end of the Z4 driving season here, I'm not going to spend any more time on it right now.
Thanks for all of your suggestions and keep your fingers crossed that it's still working for me come spring.
