Windows Phone 7, Exchange ActiveSync and error 85010014:

If you recently set a user’s password to expire so that they have to change it upon their next login, and you’re setting up their email account on a new Windows phone at the same time, you might get ActiveSync error 85010014.

Hint: It’s because you set their password to expire, dipshit!

I spent far too long reading troubleshooting guides before I figured that one out.
Hopefully this post will spare someone the same fate.