"I opened up IE (I do not use it normally) and saw that Work Offline was ticked. I noticed in another thread an issue relating to this so enabled online mode again, then restarted the installer and it started perfectly with no issues, so one solution to add to the list."
I CANT BELIEVE THIS WORKED. TRY IT NOW. DOES NOT MAKE ANY SENSE, BUT IT WORKED.
confirmed. sigh at blizzard