I have openSUSE 11.1 installed on an external hard drive connected to my MacBook via USB. I've had different *nix systems installed on a partition of my internal hard drive, and most worked fine, but now when I try and boot to the openSuSE installed on the external, I get the message "GRUB Hard Disk Error_". I don't know what could be causing this, since everything worked fine when I used different Linux distros on the partitioned internal. Any ideas?