… seven months now… been on Minefield since June last year (now b12pre), and the RC is delayed again: http://www.theregister.co.uk/2011/02/03/mozilla_firefox_4_more_betas_possible_delay/
I rarely access hotmail from the web interface so I just checked and indeed, you get into an infinite reloading loop when opening a mail. I just posted to confirm on Mozilla bug tracker and from what I read the issue is on MS side, hotmail code has been modified very recently etc…
https://bugzilla.mozilla.org/show_bug.cgi?id=631483
https://bugzilla.mozilla.org/show_bug.cgi?id=627729