Cannot boot ubuntu OS when using dual booting window7 and ubuntu

[thebluestar]

I have installed the Ubuntu into my laptop .My origin operating system is Window7. Now I have installed the Ubuntu into another disk(E , Window7 in C), but when I start the computer , it always boots with Window7 without the choices asking which OS to start
I don't know why! Please help me!
Thanks a lot!

[Xlphos]

Hello,

Did you install Win 7 before Ubuntu?
Have you tried reinstalling Ubuntu?

You could try EasyBCD, it alters the bootloader, it says it for vista but should work with Win 7. I haven't used this to boot linux neither. I would try reinstalling Ubuntu or maybe someone knows a way of reinstalling the GRUB.

[NicAx64]

you can use supergrubdisk if you want the GRUB shell and load the ubunthu kernel and load initrd and boot.

have a USB thumb drive ? then use it to boot supergrub-disk , by that you
can go to the ubunthu , in there you can replace the bootloader in MBR.

This question is discussed million times all over the internet , so do a
google search.

and there is also another method to boot linux using NTLDR directly
using windows bootloader.
Just googled and find this. and I already did that ( but not from this bellow link).
http://jaeger.morpheus.net/linux/ntldr.php

there are many choices , you can use GRUB or you can use NTLDR in
windows.

[NicAx64]

or maybe someone knows a way of reinstalling the GRUB

reinstalling GRUB is easy.

1. Boot from a Live CD, like Ubuntu Live, Knoppix, Mepis, or similar.

2. Open a Terminal. Go SuperUser (that is, type "su"). Enter root passwords as necessary.

3. Type "grub" which makes a GRUB prompt appear.

4. Type "find /boot/grub/stage1". You'll get a response like "(hd0)" or in my case "(hd0,3)". Use whatever your computer spits out for the following lines.

5. Type "root (hd0,3)".

6. Type "setup (hd0,3)". This is key. Other instructions say to use "(hd0)", and that's fine if you want to write GRUB to the MBR. If you want to write it to your linux root partition, then you want the number after the comma, such as "(hd0,3)".

7. Type "quit".

8. Restart the system. Remove the bootable CD.

In you're case setup(hd0,0) , because you going to write to the MBR.