Cannot use USB drives to install Windows 7 OR 8. UEFI mode windows 8. I Love Guns And Coffee Patch. Install Antivirus In Safe Mode Windows 7' title='Install Antivirus In Safe Mode Windows 7' />I just purchased an Acer Aspire E1. E5 5. 71. G 5. 3B1 and it came without any OS. I have two USB flash drives, one with Windows 7 and one with Windows 8. I had made using Windows bootable USB drive utility. I tried all of the USB ports, 2 are 2. I even changed the boot priority, but it always defaulted to the No bootable device found screen and forced me to turn my computer off. No matter how much I fiddled around with the settings in my BIOS, it always resulted in the same error. So, I gave up, installed Windows 8. Legacy mode, but obviously now I cannot switch back to UEFI mode, because it gives me the same problem a before. Edit This may be important UEFI boot mode doesnt recognize ANY of my USB devices. I searched the forums but I havent found a resolution befitting my problem. Does anyone have any ideas what might be the cause and what can be done to fix itHello,I am having difficulties with updating Windows 7 on my laptop MSI FX603. Windows 7 came loaded with the laptop, though I do not know if I have windows 7 basic. Protect your devices with the best free antivirus on the market. Download Avast antivirus and antispyware protection for your PC, Mac and Android. Steps to create bootable Windows 7 USB for UEFI support and GPT partitions 1. Open a command line in administrator mode 2. DISKPART 3. type LIST DISK.