System: Ubuntu 8.04 running off an external USB hard drive with
external power to the drive.

Sometimes the power gets interrupted to the hard drive - not the
computer. Yes, I know, it should be rewired so my foot doesn't
disconnect the hard drive power. Will do that, but not now.

A white screen appears with a large box and small boxes in 5 different
places. Those correspond to some kind of commands, but I don't know
which is which. No letters in the boxes. I've been shutting the
computer down and rebooting. Everything seems to work fine
afterwards, not like Windoze when many of the files are corrupted.

What key strokes can I use to shut down more safely? The desktop
doesn't want to come back up when the hard drive is repowered, or at
least I haven't found a way to make that happen. Is there a way to do
that?