I could post a 'me too'.
It appears that the 2006.1 install media (all of them) are broken on < i686 x86 CPUs
Its a known bug and is being worked. The 2006.1 stage tarballs may be affected too.
The workaround is to revert to the 2006.0 install CDs and stages and go through the update pain.
Beware - there is a suspision (not yet confirmed) that the bug is linked to the combination of mtune=i686 and gcc-4.1.1, used in the 2006.1 release media. Therefore you may want to hang off the gcc-4.1.1 update just now, if you go down this path.
I have built a base install and a few odds and ends with gcc-4.1.1 and march=k6-2. That seemed to work.
The alternative is to wait for a fix.
I'll post more when I know more - watch this thread or
this bug