New
#11
You have an EFI BIOS and if this is a Win8 machine then you also have Secure Boot. You'll need to tap the HP F2 key to enter BIOS setup and disable Secure Boot.
Then you either install Win7 in UEFI (Unified Extensible Firmware Interface) - Install Windows 7 with - Windows 7 Forums, or Bypass UEFI to Install WIn7 .
To help understand new-generation UEFI which is replacing the BIOS better watch this video: Technical Note: UEFI BIOS vs. Legacy BIOS - YouTube