I have a MacBookPro2,1 with firmware MBP21.00A5.B08. I am trying to use refit to boot linux from a 2nd internal HD. I installed Ubuntu 11.04 on the HD using another computer and installed it in my Mac laptop. When I hold the option key and select refit, the choice to boot Linux shows up. However, it always says something like "Cannot find operating system" when I try. Can you suggest what to try next?