http://www.engadget.com/2009/10/12/snow-leopard-guest-account-bug-deleting-user-files-terrorizin/ Think your Snow Leopard woes are finally over? Don't go logging into that Guest account, then. A flurry of reports have surfaced around the web explaining that even an accidental login to one's Guest account within Snow Leopard could lead to mass deletion of all user files on the primary account , and when we say "mass deletion," we mean "mass deletion." The problem goes something like this: if one