Just like KUTTAPPAN, and for the same reason, I installed Daryna on a USB hard drive. I used a live CD for that.
During intallation, I opted for not installing GRUB at all by unchecking the choice box somewhere in the advanced options' screen. Since Daryna is the only OS on this USB HDD, I thought that by not installing GRUB, I would be able to launch Daryna straight away when booting from that USB drive, without going through the options' screen where you select the operation system to launch at start up. (By the way, the installation process freezed at languages after about 80 % trought, and then again at about 95% done; but clicking both times on Skip button allowed it to continue and to complete the installation.)
But, now, when I try booting from that USB hard drive onto which I installed Daryna that way, the screen stays black, and the only message that appears is the one mentioned by KUTTAPPAN: "Grub Loading ..................... ERROR". In sted of launching Darina straight away, the system looks for GRUB !
Does it mean that you can not use Daryna without having installed GRUB ?