[CentOS] trouble installing centos 6.8

Dear all,

I'm having trouble installing Centos 6.8, in a VM using VirtualBox, and 
hoping that someone on this distribution can help.

I'm running VirtualBox  Version 5.1.4 r110228 (Qt5.5.1).

I downloaded .iso files for Centos 6.8:
- CentOS-6.8-x86_64-bin-DVD1.iso
- CentOS-6.8-x86_64-bin-DVD2.iso

I proceeded to set up a new VM, selecting Linux / RedHat 64 bit. I 
selected the DVD1 iso file above as "IDE Primary Master" and the DVD2 as 
"IDE Secondary Master".

I then clicked "Start", expecting to be able to install the operating 
system. Instead of gives me a bunch of output I don't understand, and 
then it just hangs. I've attached a screen-shot.

I tried to re-download the iso files, from a different mirror. Same issue.

Any ideas?
Thank you
Emma