Third update: The offending disk just died
How easy it is to fool oneself.
After more experimenting, I used the disk that gave me problems and installed Ubuntu 8-10 on it.
No Problem, Ubuntu sees the ide disk as a scsi disk and this works somehow.
So it must have something to do with the Lenny distro.
As a newbie that's how far I can analyse it
Hi, I have just installed Lenny, encountered a small problem...
During the first boot I get the following messages and then the boot process stops:
Aperture beyond 4GB. Ignoring
 end_request: I/O error, dev hdc, sector 0
 Buffer I/O error on device hdc, logical block 0
 ldm_validate_partition_table(): Disk read failed
I have an AMD64 X2 processor
3 disks 2 SATA, 1 IDE
2 cdrom players
Lenny is installed on the IDE drive which is the second master IDE so this should be the hdc disk.
I installed Grub on hd0
Just an update, your replies got me thinking and experimenting.
I Switched the IDE cables, turned off SMART added irqpoll and noacpi. Nothing
I removed the other drives, Nope.
I removed the IDE drive, which is in a swap tray and put in a very old 20gb drive.
This worked, Lenny installed so easily, even easier and quicker than xp
So it's either the drive or the tray it's installed in.