I have installed Kali on to an external USB HDD which installed fine. When I installed it the external installation partition was sdc,5 as I have two other hdd's in my laptop. When I boot from the same laptop everything is fine but when I boot from a different computer I just get a "Grub loading. Welcome to Grub!" message and then a flashing cursor and I am unable to input anything at all so cannot get to the grub console. Presumably this is due to the USB drive no longer being the third HDD in the system.
My question is...Is there a way of getting the USB drive load Kali no matter what the drive number is so that I can use it on different computers with different HDD configurations?

Many Thanks in advance