Somehow you installed grub to sdc so all you have to do is move your boot priority to your 2nd hdd

Well, This is odd - It's working - booting: from any one of the three hard drives, Which I can access during boot by pressing etc during boot-up, before grub should show.. I'm just guessing, but -- could this be a problem with memory?

I tried (Yesterday morning): putting /dev/sda first in line in the list of drives given in the Bios list. I tried it both with, and without having the boot flag on /dev/sda. It would not boot from any hardisk.

But this morning I tried again with nothing in the DVd tray. It booted -no problem. I rebooted into each of the other drives without error. I still have no idea what is different, or if or not something I might have done actually addressed the problem.

That's why (and the only reason why) I am wondering about some hardware issue (memory? 'coldsolder'? So far as I can see booting from hardrive is the only problem, and now - maybe not even that.

I'm going to Mark this as Solved This weekend, if it continues to work properly. After all it's really hard to diagnose a problem when you can't reproduce it. I'd still appreciate any ideas you may have, though.

I sort of gave up on this problem, and just ignored it for awhile, booting with PlopLinux. After booting I could remove PlopLinux and use the drive for other purposes. Then one day I turned it on, and it went directly to the grub menu. Now it boots easily from any one of the three hard drives. I can choose them from a boot menu by use of the esc key during the Bios portion of the boot.

Don't know what was the problem. When an ignorant piece of equipment just 'gets well' without any applied remedy, I always have the suspicion that what ever problem it had, it still has, so I don't trust it much, but on the other hand it's pretty hard to find a problem that has 'disappeared'. So I guess, I'll mark this 'solved', tho' I don't think I did anything to solve it.

Thanks for all of your suggestions. I think I have learned a little about the boot process through all of this.