Tests today produced more info.  To simplify, we removed the external hub
(although of course, the motherboard still has hub(s) on-board).  We tried grml
1.0 CD-ROM with USB devices in different combinations.

Udev is not handling the USB scanner.

WITHOUT SCANNER:
We can boot grml 1.0 CD with 1, 2, or 3 USB disks, and all of them work.  Fstab
and /mnt are fine.

WITH SCANNER:
All the USB disks fail to show up in /mnt or fstab.  Syslog shows them all
detected, but they don't get udev events (?).

HARDWARE DATA:
A brand-new Canon LiDE scanner that works perfectly with XSane and USB disks in
grml 0.9.  It is bus-powered, so could be "asleep" at boot time.  Asleep or not,
it should not cause udev failure with USB disks that are awake.

RESULT:
Our best guess right now is a udev rule problem.   What is grml's general udev
situation for USB devices like cameras, printers, scanners, tablets, keyboards,
mice, etc. (things that are not hard disks)?