Booting Problem. Windows and ubuntu on internal hdd. Centos on External USB hdd
I have Windows 7 and Ubuntu 12.04 on internal hard disk of my Dell n5010 and Centos 6.4 on an external usb hard disk.
I am having problem booting from both the internal and the external hdd.
After installation of Centos 6.4 on external hdd, i was unable to boot into my internal hdd if I remove my external hdd.
then I repaired Windows boot manager using EASY BCD. After that, my external USB hdd won't boot and the system would directly boot into windows boot loader even if i have usb hdd connected.
Please give me a solution so that I can boot into the external hdd when it is connected and boot into the internal hdd if external hdd is not connected.