Well, the plot thickens…
I just had a go, and it fails, but moreover I just tried inserting the 11.4 DVD, the one I used to install the system this machine is currently running, and that fails too, with some minor differences.
First, straight after boot, 11.4 proceeds as expected straight to the disc menu, whilst 12.1 produces:
Boot from ATAPI CD-ROM:
ISOLINUX 4.04.... et al aborted
boot:
At which point it hangs, but if I wait about half a minute, it then proceeds to the disc menu. I opt for Installation, and it goes through the usual steps, Loading Linux kernel, Loading basic drivers… all ok. After which a dialog (on both 11.4 and 12.1):
file:/var/adm/mount/boot/i386/common: SHA1 sum wrong
If you really trust your repository, you may continue in an insecure mode.
If I click OK to continue, I get continual prompts of
Make sure that CD number 1 is in your drive.
If I keep clicking okay it goes through the installation steps 1 of 6, 1 of 4, 2 of 6 or whatever. This seems a little more smooth with the 11.4 disc, but ultimately it ends up at:
An error occurred during the installation.
If I select Start Installation → Start Installation or Update → DVD/CD-ROM, I then get
No repository found.
Is it reading exclusively from the disc at this stage or is it analyzing anything on my hard drive? Because the basic hardware remains the same from when I installed 11.4 previously with the same disc and DVD drive.