“A fatal error occurred while trying to sysprep the machine” error

This occurs when a Windows 7 system has been sysprepped three times — KB929828. To overcome this, you will need to do the following: Run the slmgr.vbs -rearm command. Try sysprep again.   Additional ressources : http://technet.microsoft.com/en-us/library/dd744512%28WS.10%29.aspx http://mickitblog.blogspot.ca/2011/08/fatal-error-occurred-while-trying-to.html