Once the system is encrypted, and rebooted, the two Bootguard screens are presented sequentially.
The first Bootguard screen is for MBR systems, which is the gray screen. Once the pass phrase has been entered on this screen, the yellow UEFI Bootguard screen is displayed. Once the pass phrase is entered into the second Bootguard screen, the system will not boot, and will display the error, "Missing Operating System". Only one Bootguard screen should be displayed as a system can only be MBR or UEFI and cannot be both.
Many of the new Systems come with UEFI drives, which allow for larger drive sizes as one of the advantages of this system. Both Windows 7 and Windows 8 have the capability to be UEFI systems, however Windows 8 is much more common and has the most compatibility included with this system.
MBR Bootguard Screen would come up first:
Once pass phrase of first screen was entered, UEFI Bootguard Screen would come up second:
The Lenovo BIOS has some configuration settings that have to do with the boot ordering of systems. This system has the capability to boot both MBR and UEFI systems. As part of the settings, Boot Mode is available, which defaults to "Auto". Auto means the BIOS will attempt to detect which technology is being used. In the case of the Lenovo M73, the system was UEFI, however the Auto setting was detecting the drive as a Legacy drive, or MBR. Since the drive is actually using UEFI, the system would not boot properly.
Due to the way this BIOS was configured to automatically detect MBR (Legacy) or UEFI, both Bootguard screens were being displayed (MBR and UEFI).
Lenovo p310 - 1TB 7200 RPM HIDED
In order to resolve this, the BIOS needs to be configured to boot "UEFI first", which will not attempt to load MBR first, and allow proper booting of the system with only one Bootguard screen and proper processing to the operating system:
After making this change, the system should properly boot up.
Lenovo Dual Bootguard Screens
Dual Pre boot Screens