5.0.1 boots, but 4.0 does not (HP t3640)

Hi everyone,

I have a CD and a DVD of Knoppix 5.0.1 .
Both pass the "knoppix testcd" test.
Neither will boot my machine, and both fail in
the same way: "autoconfiguring devices" gets stuck,
with the green bar getting longer and longer until
it hits the right-hand side of the screen. I have tried
knoppix failsafe and a few other options, without
success. Control-C does not help.

On the other hand, I have a Quantian 0.7.9.2 DVD,
which will boot my machine with "knoppix wheelmouse".
It seems to use Knoppix version 4.0, and works with no
apparent errors other than the known problem that can
be fixed with the "kdesktop" command.

I would be grateful for advice on how to make my 5.0.1
work.

This is the machine spec (according to the sticker on
the box):

HP Pavilion Media Center t3640.uk
Genuine Windows XP Media Center Edition 2005 with Update Rollup 2
Intel Pentium (R) D Processor 820 Dual core
2 GB DDR2-SDRAM
160 GB SATA 3G Hard Disk Drive (7200 rpm)
NVIDIA (R) GeForce 7300 LE TurboCache with PureVideo
technology - up to 256 MB video memory
IEEE 1394 FireWire(R) interface

... and some other stuff that I suspect is irrelevant.

Thanks!
David Pearson.