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QUICK-SWITCHING USER ACCOUNTS. One reported quirk affecting shutdown is the three-account shuffle. Windows XP gives the ability to rapidly bounce between user accounts, with Win+L. If at least three user accounts exist, and you quick-switch through all three, and then log off all three in reverse order — “backing out” in an orderly way — then the machine may hang on shutdown. There may be other variations of account shuffling that cause this, but this one, clear example was provided by newsgroup correspondent John Ward. Microsoft has now identified something similar as a bug, in MSKB 320008, “You May Not Be Able to Shut Down Your Windows XP Computer.” The situation they describe is that only one user is logged on, quick-switching is used, and “Windows is under heavy stress.” A supported patch is available; see the article for details.