Have you checked that the LiveCD image is not corrupt (dodgy CD burn or
download)?
I helped installing Gentoo 2005.1 on a SATA machine last weekend and we were faced with similar problems. No segfault, but after chrooting the disk was no longer there, and errors arose while trying to write to it. After a few tries, the solution was to download a new CD and check if it was corrupt, along with the stage file and portage tarball used. You should try this, if you didn't check it in your prior installation.
HTH,
Fernando
