This is driving me crazy. I have followed the instructions and made a USB pen drive of Acronis. Then made the image of that, and put in on external USB HD. I have tried the HD on several systems, all boot from it with the expception of one. But that one will boot from the USB Thumb drive. When I try to boot form the USB HD, it tells me "missing oeration system" I have tried this on 2 different PC of the same make and model. Same result. I have upgraded the BIOS on one. and tried changing setting in the bios. Is it possible that system does not like the USB HD, I have tried 2 different USB HD, when I hit F12 to select the boot device I want, it does ID the drive by make and model. So i know the BIOS see it. Help, I am out of options that I can think of.