Thanks, @CharlesV . Although I didn't say so in my original post, I have tried actions on those lines already, but they don't seem to have made any difference. I used to have both MX and Mint on this old computer, and encountered difficulties with booting up. So in an attempt to simplify matters I wiped and reformatted the hard drive and then installed MX 23.5 alone, using the default settings, as a clean fresh install on the whole disk (ie with just the / (root) and /home partitions). That's how the setup is currently configured.CharlesV wrote: ↑Sat Apr 19, 2025 4:56 pm MX Boot repair will give you a few options to try, you might start there and see if either reinstalling or repairing grub might help.
This issue sounds to me like something is possibly running the wrong grub? and then eventually figuring it out. If you can wipe the drive, that might be another method to see whats up - wipe the drive and then reinstall.. and personally I would install into one partition / and see if that helps things.
I assume that this default installation puts the MX Grub into the MBR (which is I think the norm). I noted that MX had a Boot Repair tool, so I tried that. It gives the option of reinstalling the [repaired] Grub into the MBR and/or the partition containing MX 23. I ticked the boxes for both. I may thus have two Grubs (how do I check?) . But neither appears to function automatically when I try to boot up from the hard drive. And I am still mystified by the error message which refers to "....failed attempts to read or write outside of disk 'hd0'" . What does that message actually mean?
