Input-output error when booting after installing YDL : problem with Open Firmware?

[René Bourion]

I posted a message on the same subject on April 10th, but no comments were
forthcoming. I repeat my complaint today, as things have become worse and
worse.

My machine is an iMac rev. B with 160 Mo of RAM and a 20 Go HD.
I did a very careful installation from the YDL 2.2 CD, the partitions being
as follows:

-- 4 Go in HFS+ for Mac OS9;
-- 1 Go in HFS for transfer between Mac and Linux, to be mounted as /giga;
-- 10 Mo for boot;
-- 256 Mo for swap;
-- 6 Go for /;
-- 6 Go for /home.

As the final step, I set the default in yaboot as MacOS 9. When the machine
started again, I got this:

welcome to yaboot version 1.3.6
boot: linux
Please wait, loading kernel...
/pci/mac-io/ide@20000/disk@0:10, /boot/vmlinux : Input-output error

and nothing more.

What is puzzling is that
    a) this same disk was more or less working a little time ago;
    b) an attempt to use the YDL 2.1 CD gives now the same result.

The message looks like Open Firmware language: is it possible that the
Firmware on my machine has got corrupted? I have run the iMacFirmwareUpdate,
but it says that the Firmware is ok. On the other hand, I have noticed that
the MacOS seems to take rather a long time to load: but are those things
related?

Can somebody make any suggestions to solve this problem? I should be most
grateful.

R.B.