grub-installer isn't dealing properly with the non-ASCII character in the description of your Windows partition returned by os-prober. From the log:
Apr 14 20:22:41 grub-installer: info: unhandled: /dev/discs/disc0/part1:Microsoft Windows XP Apr 14 20:22:41 grub-installer: info: unhandled: dition familiale:Windows:chain
grub-installer isn't dealing properly with the non-ASCII character in the description of your Windows partition returned by os-prober. From the log:
Apr 14 20:22:41 grub-installer: info: unhandled: /dev/discs/ disc0/part1: Microsoft Windows XP Windows: chain
Apr 14 20:22:41 grub-installer: info: unhandled: dition familiale: