At what point does it fail? Is it early in the build, or late? What's your build command line?I use Kubuntu's own kernel build via the command "make-kpkg --revision=1 kernel_image kernel_headers". It fails at the very early build stage. When issued this command, just after few lines and then it fails. Today, I will try the same .config with recently released rc5 and will let know the result.
J