I have a multi boot system, three systems each on their own drive. The original setup was install oldest to newest. That was w7p (Gaming OS) w7u (video, photos, sound editing OS) W10 (everything else OS). All worked good as I had to set the bios to legacy to use the Microsoft boot loader. Well the mother board had an issue just after the fall feature update failed to install, no sound. I sent the board back to Asus for repairs where they updated the bios and the firmware and it has been messed up sense then. Still no sound. I had all sorts of entries in the bios to boot to the CD/DVD 6 entries, a flash drive 6 entries, after much reading I was able to get P-5 the w10 G:\ drive positioned for first boot. It appears now that the system is using EFI boot loader to boot. I have all three listed to launch from each one, and it did that for a while then all of a sudden I try and launch w7u, I get check disk and it proceeds to delete thousands of entries and reset the ids. Now it won't boot, how do I fix this? Separate the drives and just do a cd repair on it or change the BCD.