Closing.  The problem is the scanner and CONFIG_USB_SUSPEND as reported in
Ubuntu 2.6.20.

https://launchpad.net/ubuntu/+source/sane-backends/+bug/85488

It's not the modules, it's not the hub, it's not the PC hardware, it's Linus
getting too excited about laptop features.

Linus should not have released this buggy flag.  These scanners all worked fine
for a long time in Linux.  Vendor hardware is buggy to an extent, but as Linus
likes to say about his kernels, perfection is impossible and that's the real
world, so deal with it.

Testing 2.6.21 was never useful to us at all.  The right test was to recompile
2.6.20 with the flag off.  That's been my focus as time allows.  But GCC keeps
segfaulting even with 1.5 GB of RAM.  We're still running grml 0.9.

For us the fix is to remaster grml 1.0 with the flag off, if GCC will cooperate.
 We're a little worried about some other XFS bugs reported in the late 2.6.22
rc's so we are going to watch kernel things more carefully in the future.