I've read through many forums how to do this, but it doesn't seem to work. I keep my internal hard drive attached, and I install Ubuntu to my external hard drive fine, but when the installation tries to install GRUB, I get an error message. I've even tried clicking on the advanced button and telling it to install at /dev/sdb but I still get the error. If I take my internal hard drive out during install would this help?Any takers for what might be going on? ThanksSorry I don't have my laptop with me at the moment. However, I have tried installing GRUB to the internal hard drive already (accidentally) however, I get "Error 21" when I try and boot my computer. Even with the external hard drive connected. Am I missing something?