Could you click this link and let me know what happens http://login.live.com/login.srf?id=2&svc=mail&cbid=24325&msppjph=1&tw=0&fs=1&fsa=1&fsat=1296000&_lang=EN&lc=1033
This seems to be a common issue since microsoft went on their latest push for Live Mail.
When you get time tomorrow try this suggestion.
Click on the Safari Menu and then choose Empty Cache
A dialog box will appear, click on Empty
Once completed, Click on the Safari Menu again and click Preferences
From the Security Dialog box click on the Bookmarks button
Then click on the Show Cookies button
Click on Remove All
Click on Done and close Safari, Then reopen and try logging in again.