Now I tested installation of the latest snapshot 11.08.2015 in both, MBR mode and UEFI mode. * In UEFI mode the boot stick gets stuck in the "Loading ramdisk" phase, just as the installed version. * In MBR mode the installation/boot menu freezes. On the mailing list it was suggested that bug https://bugzilla.opensuse.org/show_bug.cgi?id=913996 might be related and that I should try to boot without related microcode changes using the dis_ucode_ldr Kernel parameter. This did not affect the issue.