http://www.microsoft.com/downloads/details.aspx?familyid=be596899-7bb8-4208-b7fc-09e02a13696cObstensibly called "Microsoft Exchange Server Error Code Look-up", this is a cool little tool for looking up those irritating Microsoft errors like -2147217406. It's not perfect, but it should at least guide you down the path of what the error may be, based on what you were doing.
(Also works with WSUS error codes.)
![[info]](http://l-stat.livejournal.com/img/userinfo.gif){kind=small}