Intel Virtualization technology problem

Hi, I'm trying to install a VM on Virtual Box and need to enable virtualization in order to do this. My mobo supports it (ASUS P8P67LE) as does my CPU (i5-2400). But when I go into the BIOS to enable it (it's defaulted to disabled) it won't let me change it, I can't even highlight that particular menu item. any ideas???? I appreciate any help. :)