That's the reason. Macbook can't use gfxgrub which is used in Daryna. I have suggested we skip it in the future due to this problem.macbook
The solution is to install a normal grub - look here
http://www.linuxmint.com/forum/viewtopi ... ub+macbook
The link in my answer gives an in depth explanation - and it's not hard to do, just an annoynance for macbook users. Note that dual boot with mac gives extra problems