Hello,
Good news:
With the lenny installer 5.0.3, installation was successfull.
I assume, that the change
* sata_nv: avoid link reset on controllers where it's broken
(Closes: #498271, Closes: #501023)
has corrected this issue, because booting from CD was failed.
And the DVD-ROM is connected to NVidia SATA.
This bug report can be closed.
Thank you for the great work.
Regards
Bernhard