I have installed ubuntu 12.10 in a WD external harddrive (320GB). This is a complete installation, not live USB.

When I plug it in my HP desktop I go to the BIOS settings and boot off the harddrive, everything work perfectly -as it should. Now this works on everysingle computer and laptop in my house (all HP) -except for ONE. My HP ProBook 4530s.

When I select to boot of the USB I get the Message:

error: attempt to read or write outside of disk 'hd0'

Now, I have removed the hdd from my laptop and the external drive is the ONLY drive plugged in. Bellow is a picture of the screen. After the message I navigate to ls / (as shown below):

After here I try to acces other folders under ls /, for example, I try to go to ls /boot to get to the grub folder. Then I get the same message as before: as shown by the image below:

The only folders I can access without getting the message again are /home, /run and /usr.

So how do I:

1. Boot Ubuntu from GRUB2 (this screen) manually
2. Set to automatically boot Ubuntu
3. If possible an explanation for this problem

Thanks!