Just before signing into xbox.com for no reason at all its asked me to change my password.
Possible spam issues from your Hotmail account.
Third case today that Ive heard now.
Happened to me too today.
I got the same also... Maybe the downtime was engineered by hackers, and changing our passwords was a result of lost information and an attempt to re-secure our accounts ;).
On the other hand its a bit odd....
I got the same, so after the prompt of changing it the first time, I then quickly went into my hotmail account and changed it again, just in case!
I got a prompt from my hotmail account and had no choice but to change it.
Seems MS have set up a new function in there requiring you to change your password every 72 days to your hotmail account.
You can untick the box and opt out of it, but it didnt give me that option until after I had changed my password.
Yup i had it today too, didn't want to change it at first as i've never had this sort of thing happen but had no choice