I am using the install-x86-minimal-2006.1.iso with an md5sum of 91a1b475d4c0d4e843990509c629c43d booted with no options.
It works fine for me. Have you tried verifying the burned CD against the provided digests? It may be a bad burn or even a crappy CD-ROM.
I still get the error when using newer media or a different burner, but it isn't too serious as the system continues to boot up. The problem will probably disappear with an updated release.
Oddly enough, using this CD on another x86 machine does not produce this error.
Sounds like a crappy CD drive to me :)