This was the command to insert the language pack into the wim file Dism /image:%systemdrive%\work /add-package /LogPath:AddPackage.log /packagepath:win7_x86_en.cab This is the info of the index I was trying to install with Winntsetup ... I also have the lang.ini in the sources folder, but I dont believe Winntsetup cares for it. I cant test it another time atm or see the exact details of the crash... but if I had to guess I would say its because I didnt use an english image and added the portuguese language, but did the other way around and somehow that messes up something when trying to apply that image instead of installing it. -edit- Since I couldnt try again, i've made some digging and found this: http://technet.microsoft.com/en-us/library/dd799255%28WS.10%29.aspx That could explain it =)