"No operating system found" external harddrive installation

[sdrsdrsdr]

Hi all,
I have been trying to install 11.10 on an external drive.
I am running windows 7 x64 as my primary OS.
I go through the installation procedure for Ubuntu and it seems to go ok until I restart and then I get the error msg "no operating system found". I have set my bios settings to read from external drive. I have 4 partitions set on the installation drive /boot, swap, / and /home. I have set the boot loader to the external drive.
any help appreciated

[raja.genupula]

please produce us the output of bootinfoscript which is in my signature .

Thank you