Sorry to hear you had to reinstall. Not sure what updates fixed my problem, but the windows updates on 5/14/2014 fixed my problem. Restart is back to normal.
Hey wanted to bump this up because I am having the same exact issue, after the last update to 8.1 restart takes for ever, system just hangs forever. If I power down it restarts like a bandit, but I do not want to power down every time. XPS 8500 8Gigs of ram. Ati radeo 7570.