I did the following on my own ;-) but I see that Old-Polack had the clue!
This morning I turned on the computer and said to myself: I have reinstalled several
packages, to no avail, but the thing I have not reinstalled is... grub.
So I opened Synaptic and did just that, and got an error message,
something about (hd0,4) no mapping in device.map
Looking in /boot/grub there was no such file, but there was an old
version named device.map.backup, which contained:
So I copied that to device.map, and rebooted.
YES!!! Both problems solved in one swell foop!
My grub came up with the graphic menu, and when I went into
"Configure your computer" it opened "Set up boot system"
with no problem at all!
Lesson learned: If grub has problems, either in configuration, or
the actual boot process, check for device.map problems.
Thanks for all the time spent helping me out on this!