I got to this issue on Ubuntu 12.04.5 amd64 host and Ubuntu 15.04 beta2 guest.
What I did: 1. I downloaded official Ubuntu 15.04 beta2 iso (MD5SUM e838edda85712d283bd94b34dbb5d6ec) 2. launched "usb-creator-gtk" for creation of LiveUSB, selected ISO and target USB-flash, pressed "Make Startup Disk" 3. LiveUSB was created ("Installation Complete" window) 4. Pressed "Test Disk" 5. Got error message in QEMU window ("gfxboot.c32: not a COM32R image") If I enter manually "live" I get into other issue with VGA adapter ( "The system is running in low-graphic mode" see bug 1437740 ). So "usb-creator-gtk" from Ubuntu 12.04.5 Precise Pangolin produces Vivid Vervet image that is unusable in QEMU/KVM. Please fix this bug in all LTS versions of Ubuntu - 12.04 and 14.04. ** Tags added: precise -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1325801 Title: failed to boot from USB disk with error: gfxboot.c32: not a COM32R Image boot: To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-cdimage/+bug/1325801/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs