Preupgrade problem with kickstart file

[Timothy Murphy]

I've upgraded to Fedora-10 without problem on 3 computers
- all Thinkpads - using preugrade,
but it has failed on 3 other computers, with the same error:
after running preupgrade, and re-booting, I get the error
"Unable to download the kickstart file".

These are 3 very different computers -
an ancient  SCSI only PIII machine, an Athlon64 machine,
and a 32-bit AMD machine.

Surely I can't be the only person getting this error?

If I go on, pressing Cancel and entering what it calls
the interactive installation, things progress reasonably well
until I enter what I assume is the graphics mode,
when the system seizes up,
with the mouse not moving and the keyboard lights flashing.

When the program says it cannot "download" the kickstart file,
does it mean it cannot find or read the file /upgrade/ks.cfg
(which is indeed in the place it specifies, and is readable)?
The word "download" seems a little odd if that is what is meant.

Also, it suggests that I might "modify the kickstart parameters",
but I have no idea what this means.
Is there in fact anything one can add to the grub kernel line
which might improve matters?