minor addition. i plugged in the disk today for testing, and left it there, and it didn't freeze. it played the on and off game for about 40m (sd0 detached 48 times) at which point the kernel disabled the port in question.
so i cannot reproduce the crash every time. has anyone ever seen something like this before? i'll test a new cable and a snapshot asap. (but as i said, the disk looks fine in windows, so i think it's not the usb port/cable, but i'll do some more tests) -f -- the first sight of love is the last of wisdom.