[CentOS] Two CentOS installations failed dual boot

Hello everybody,

I installed Centos 6.2 on a computer with an older version of it in order to dual boot both of them. I managed to install the new OS on a physically seperated hard drive, and configured grub to make the newly installed OS the default one. Now the older OS won't boot and this error message shows: *"error 13: invalid or unsupported executable format"*. I attached to the email the output of *"fdisk -l"* and a copy of the *"/etc/grub.conf"* configuration file.

I have no experience dealing with boot/grub issues, so any help on this will be much appreciated.

Regards.