usb umass regression

My system now locks up again when I attempt to write to my pendrive
without going into the debugger or any output to console at all:

Oct  6 13:24:32 server kernel: da0 at umass-sim0 bus 0 target 0 lun 0
Oct  6 13:24:32 server kernel: da0: <Memorex USB2 Thumbdrive 2.00>
Removable Direct Access SCSI-2 device
Oct  6 13:24:32 server kernel: da0: 1.000MB/s transfers
Oct  6 13:24:32 server kernel: da0: 125MB (256000 512 byte sectors: 64H
32S/T 125C)

mount -t msdos /dev/da0s1 /mnt

I used tar:

cd /mnt
(cd /; tar cf - var/named/etc) | tar xvf -

Sean