When installing the package syslinux-themes-debian and I could install linux-image package, the package for a directory that was not available. Uninstall the memtest86+ and uninstall the above package syslinux-themes-debian. Then there is a mistake, as recommended extlinux syslinux-themes-debian. And if you delete memtest86+ displays the original error. Greetings. Marcos Delgado.