I was tasked with a project in which this forum helped guide me so I'm going to post my results. I was given a acer laptop whose partition arrangement was "GPT" vs "MBR" and our encryption software did not support it. Since it is an OEM install with recovery partitions etc... which weren't needed, I nuked the acer junk and coverted the drive to MBR with paragon drive backup server v10. The conversion was a success and the OS partition was intact, however it would not boot. I went through the steps here to correct the MBR and rebuild the BCD. The computer would come to the same hardware device not found stop error and give the option to press enter or esc. I pressed enter and the OS booted "Windows 7 Pro x64." After much head scratching, I looked at the windows partition in disk management and it was shown as a logical volume and not active or primary. A EIF partition of 300mb was also shown. Both partitions contained boot info, crash dump etc. I located a free program which let me manipulate the partitions called MiniTool Partition Wizard Home Edition. I put the drive in a SATA dock on my shop computer nuked the EFI partition and expanded it to the whole drive. I then marked it primary and active. I put it back in the laptop and the stop error went away, however, the bootloader was missing. I booted to the recovery console and fixed the MBR. It booted up without error and encrypted without data loss. It appeared that the OEM boot partition was the active partition with hooks to the OS and OEM recovery partitions and was the active primary partition, so when I nuked it, the OS wasn't found because it wasn't on an active primary partition. Long story short, make the partition active and primary and repair the MBR with whatever tools you need to, startup repair will do it for you if you don't want the command line stuff. I hope this helps.