Nice explanation, I ran into this at one point myself.  Here's stumper on a completely different admin issue, I'm guessing this is just a glitch, but maybe not?

I tried to login using to admin.microsoftonline.com with admin@example.microsoftonline.com.  I got the "your password has expired, please change” screen.  I then tried to change it but was told my "old password was incorrect".  I retried many times assuming I mistyped, but had the same problem.  Finally, figuring I was going crazy, I typed my password in the clear in notepad, and copied it to the clipboard.  I logged in again, this time with the pasted password, and got the change your password screen as expected (so I knew the password in the clipboard was correct).  I pasted the SAME password in as the old password on the change password screen.  I still got the "your old password is incorrect error".  I finally called support--this was greatly disappointing and worse than unhelpful, but that's not the issue here (ticket number 100908-000108 if anyone at Microsoft Support cares to investigate).

I finally figured it out myself while going on and off hold.  I logged in using my own personal account (not the admin one).  Fortunately, I had previously enabled admin access for myself and reset the admin@example.microsoftonline.com password from there.  It worked and I can get into my admin account.  Is this some glitch or by design?  I couldn't quite understand what the problem was.  

And yes, to avoid some questions:

- I am 100% certain I typed my username and password correctly (multiple tries and then I used the clipboard).

- I was getting a "your old password is incorrect" error when trying to change my password, after using the same password to login successfully and get that far.  I was not getting any errors on the new password not meeting any sort of complexity or match requirements.

- I’m not *usually* an idiot. :)

But, other than this specific issue and the quality of phone support, I must say I am really pleased with the service itself—your technical guys deserve a lot of credit for making this work so well.  The rest of our company barely knows we don’t have our own exchange servers (especially since the login tool remembers passwords :)

I had exactly the same issue with my admin account - and like you Im not *usually* an idiot :)

the only way I could resolve was to use an alternate admin account and change my password - certainly less than ideal. Ive got an open action with our BPOS contact to expain the situation..