Microsoft getting snotty with Apple's Safari
Microsoft is locking Safari users from its Hotmail service.
Recent changes to Microsoft's Hotmail service appears to have left Safari-using Mac users out of luck. Currently, logging into Hotmail with a Safari browser causes an infinite redirect loop (or stops when Safari has said "enough redirects!").
Microsoft is big on interoperability, Apple. Try entering into a(nother) patent agreement with the company. That seems to do the trick.