[ubuntu] Grub missing

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http://ubuntuforums.org – Dear brothers in Ubuntu, I ins talled Ubuntu 12.04 (Unity) in my PC in which I also have XP Evo, but in re-starting I get a black screen with a warning of GNU Grub version..., saying: "Minimal BASH-like editing line supported". If I click Tab, it then gives me a bunch of command lines. I don't know what to do. Could anyone, please, help me out so I can get Grub selection page? Thanks, Tin (Hardware)