Want to make Yosemite freeze on shutdown?

[nkalister]

run this command on your FileVault 2-encrypted Mac:

defaults write /Library/Preferences/.GlobalPreferences MultipleSessionEnabled -bool false

oh, apple.

[nkalister · Accepted solution]

Now that you're broken, you may be wondering, "How do I fix this?" Or, possibly, "how can I stab nkalister in the eye now that he's broken my mac?"
Well, put that fondue fork down. There's an easy, COMPLETELY logical fix.
<edit: the MCX reset was unnecessary, MCX script removed>
Either create/delete an admin user from System Preferences (you do not have to delete your current user account!) Or decrypt the entire disk from the Security SysPrefs pane or using fdesetup.