Original post : BootGuard GPT Partition Protection (BG-4PP).
BootGuard by NeoSmart Technologies
This PC has been prevented from booting in legacy mode to protect your data.
Please re-configure your UEFI firmware (aka "BIOS setup") to boot in UEFI mode.
Error Code: BG-4PP
More Information: http://neosmart.net/wiki/bootguard-4pp/
Press CTRL+ALT+DEL to restart