Oui, pareil au redémarrage (qui se fait tous les matins)

DiskStation> fsck.ext3 /dev/root
e2fsck 1.40.3 (05-Dec-2007)
/dev/root is mounted.

WARNING!!! Running e2fsck on a mounted filesystem may cause
SEVERE filesystem damage.

Do you really want to continue (y/n)? yes

fsck.ext3: No such file or directory while trying to open /dev/root

The superblock could not be read or does not describe a correct ext2
filesystem. If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>

J'ai essayé au lieu de /dev/root : / et rootfs => même chose.
Et bizarrement, /dev/root n'existe pas...