It turns out that the script ZTIBde.wsf was modifying something and that the language of the boot loader was set to fr-CA. fr-CA do not exist for that setting, fr-FR must be the one used to be in french.

I am using OSD variable in my Task Sequence to set regional settings. My unattend.xml is using the following variables: %OSDUILanguage% %OSDSystemLocale% %OSDUserLocale% %OSDInputLocale% I have those variables set in my TS. UILanguage is set to fr-FR and all the others are set to fr-CA. All the settings seems to be applied during the TS and the boot loader language is in French as set by the fr-FR setting. After the final reboot, the boot loader is in English because the value got changed from fr-FR to fr-CA which does meen nothing for the system in that setting. Like I said, during all the TS the boot loader is in french and there is nothing else related to language after the Setup Windows and ConfigMgr part. There is no Windows Update done and no software is getting installed. I have a setup replicating the same steps in another lab (Windows image, Offline language pack, set all the same variable, capture, deploying the captured image specifying on the UILanguage variable) and the result is that the boot loader is in french. Any idea on what could change that value from fr-FR to fr-CA? Any help would be awesome! Mat