Want to install centos 6, but got grub message, what is grub

[fastestinworld]

I am sucessfully install centos 6 or centos 5 in many servers before

but in a server, i tried using centos 6.7 & 6.5 installation dvd (the same dvd i use for many servers), the installation page is not appeared
only got this grub message, what is grub? this is my first time got this





then i tried using centos 5 installation dvd in this server, the installation page is appeared
but i need to install centos 6.7, what should i so the installation page is appeared?

[gerald_clark]

Check your BIOS and make sure you are booting off the DVD and not some leftover junk on the hard drive.

[fastestinworld]

update :

i am sucesfully install centos 5.5 64 bit in this server, no grub message




just when i tried to install centos 6, always got grub message in this server, what should i do with this grub, so i can install centos 6? help please



i already tried deleted some boot options, even tried deleted all options except CD/DVD ROM, but still got grub message

[TrevorH]

Check the iso file that you downloaded is correct before you burn it to DVD. There are files containing the correct md5sums on all the mirrors, in the same directory that contain the iso files themselves.