grub2 - Grub rescue problem after installing Ubuntu 12.04 LTS

I have dual boot with Window 7 And Ubuntu 11.10.

Yesterday I tired installing Ubuntu 12.04 LTS , by Manually removing all Ubuntu 11.10 partitions, creating new partitions and installing Ubuntu 12.04 LTS, But then I got this error.

error: unknown filesystem
grub rescue >

The thing is when I let Ubuntu do partitioning for me it solves the problem, But I always do my own partitioning and it was working with me before, what had changed in Ubuntu 12.04 LTS?

I have both Windows 7 And Ubuntu 12.04 LTS on same Hard Drive, And the Partitions for Ubuntu that I have are :

1. /


2. /boot


3. swap


4. /home

I am not an experienced Ubuntu user And I hope I am not missing any necessary details, But please feel free to ask.

Thanks in advance

Now its working, sorry for my newbie question but i figured out that boot loader wasn't installed on the same hard drive where my Ubuntu is installed.

Thanks.