Folks, Have patience, Cross your fingers....
This has happened before and then again now.
I am getting the same error as of yesterday. Just prior to this message I noticed this error that said something like the site is undergoing maintenance.
My guess is that hotmail is migrating to the latest exchange server and that comes with the usual set of architecture and migration of millions of user accounts such as yours and mine. It might take a few days given that we are all free customers, It might never happen as possible the migration expert dumped all our .pst files. Assuming that each hotmail account is held in .PST files.
This is just my guess and theory. Anyways , I always try to duplicate mails and have it stored in yahoo, gmail etc... That way if all the corporations conspire to eliminate free email users, at least there might be one dissenter who will provide free email.
Until then , user a free tool like thunderbird or other email client to download all the emails as soon as you have obtained access. ..
Good luck and patience until then.