Etch USB installation errors

[Nick Russo <nick@cs.uchicago.edu>]

I've been installing Debian Etch from a custom generated USB image, but
I run into two odd problems when I try on a certain AMD64 machine.

 1) When I use Ctrl-Alt-Del to switch between virtual consoles during
    the install, eventually it starts drawing to the wrong consoles.
    For instance, when I'm looking at a text console, red and blue lines
    get drawn which are probably supposed to be on the progress window.

 2) The USB filesystem gets corrupted, while my preseed/late_command
    script runs. Running ls -lR on /hd-media/ exposes the fs corruption,
    even if I move the USB stick to another machine.

I tried installing the same release on the same machine using a netinst
CD, and it worked perfectly.

I'm focusing on the second problem, as it's a show-stopper. This it the
late_command I'm running, and I can see corruption before the cp -pr
even finishes, so I don't think foo.sh is causing the problem.

 d-i preseed/late_command string mkdir /target/local; for dir in preseed \
   packages; do cp -pr /hd-media/$dir /target/local/; done; in-target sh \
   /local/preseed/foo.sh; umount /target; reboot

When I comment out that late_command line, I still end up with a corrupted
USB stick.

The only other substantially customized item in the cfg file is an early
command to get a proprietary hw raid driver:

d-i preseed/early_command string cp /hd-media/drivers/2.6.18-4-amd64/rr232x.ko \
 /lib/modules/2.6.18-4-amd64/kernel/drivers/scsi/rr232x.ko; depmod -a; modprobe rr232x ||:

Are either of the above symptoms familiar to anyone?

Thanks for any hints,
Nick