Oui, justement j'ai fait un dual-boot donc grub est inscrit en partie dans le mbr.
Au démarrage, j'ai la *fameuse* indication :
no such partition
* Master Partition Table: This small bit of code that is referred to as a table contains a complete description of the partitions that are contained on the hard disk. When the developers designed the size of this master partition table, they left just enough room for the description of four partitions, hence the four partition (four physical partitions) limit. For this reason, and no other, a hard disk may only have four true partitions, also called primary or physical partitions. Any additional partitions must be logical partitions that are linked to (or are part of) one of the primary partitions. One of these partitions is marked as active, indicating that it is the one that the computer should used to continue the boot process.
* Master Boot Code: The master boot record is the small bit of computer code that the BIOS loads and executes to start the boot process. This code, when fully executed, transfers control to the boot program stored on the boot (active) partition to load the operating system.