[ubuntu] Cannot boot after installing alongside Win7

view full story

http://ubuntuforums.org – Today I tried to install Ubuntu 11.10 x64 to my Sony Vaio F13 series. The problem is, Windows is installed to the C: drive of my computer. However, when I choose to install Ubuntu alongside Windows 7, ubuntu recommended me to install to D: drive. After I installed Ubuntu, there is no option to boot in Ubuntu. It just boots into Windows 7 which I do not want to. How can i fix this problem? (Hardware)