Not real sure, but just a thought, could the laptop possibly be using SATA for the hard drive connection?
If that is the case, I think that the drive might be /dev/sda (like I said, I'm not sure). Can you check the fstab file to see what the system is calling the partition that / is mounted to?
Also, the command 'fdisk -l' should list the partitions on the physical disk. Might give that a try.