Background reading material: How to analyze the log file entries that the Microsoft Windows Resource Checker (SFC.exe) program generates in Windows Vista: http://support.microsoft.com/kb/928228 Aaron Stebner’s WebLog : Steps I use to narrow down an OS update installation failure on Windows Vista and higher: http://blogs.msdn.com/astebner/archive/2009/03/12/9472695.aspx One of the big changes between XP and Vista/Win7 is the patching stuff one looks at.  In XP/2k3 you’ll be asked to look at the windowsupdate.log file and the KB######.log file (that’s typically the Knowledge base article number).  In Vista and Win7 (and 2k8) Windowsupdate.log is still there, but the patching stuff is in the Component Based Servicing logs or CBS.log for short.  Me being a member of the TV generation sees “CBS” and thinks the television network. It’s not that.  But everytime someone says “look in your CBS log file” that the very first thing I think of. You’ll find two logs in the C:WindowsLogsCBS folder One called CBS.log, the other CBS.persist.log.  CBS.persist.log is the older of the two and is generated when the cbs.log is around 35-40 megs.  It’s normally a few weeks older