If an install is restarted after the stage tarball has already been fetched and unpacked one cannot simply point the installer at the existing tarball in /mnt/gentoo because in the restarted install as it tries to overwrite it with itself: GLI: May 12 2007 06:51:59 - Error: `/mnt/gentoo/stage3-amd64-2007.0.tar.bz2` and `/mnt/gentoo/stage3-amd64-2007.0.tar.bz2` are the same file
this is a known issue. restarting support is very primitive for this release and does not work very well in a lot of situations. I will make a note to try and fix this for the next release.
This particular restarting issue will be fixed in 2007.1.