A couple of months back i bought a new dell alienware X51 desktop, assuming that my ubuntu 10.04 would boot on it out of box. I was wrong. It seems that the BIOS in X51 alienware desktop(A01) does not support old legacy bootloader's that are used to boot ubuntu on the older PC's. Therefore to fix this problem first we need to download and install the newly updated BIOS(A02) from the following link on windows. http://www.dell.com/support/drivers/us/en/19/DriverDetails/DriverFileFormats?DriverId=JMX4R&FileId=2882590626 Once done, Plugin your Ubuntu external harddrive or USB. Reboot your PC and now you should be able to see the updated A02 BIOS. while booting press F2 to enter into the BIOS settings, change the bootloader to Legacy bootloader, Save and Exit he Bootloader configuration. For new ubuntu installation please refer the following link http://quantumbeach.wikidot.com/bug:1 Ofcourse in my case i had to boot Old ubuntu 10.04 installation. For that once we