ILLEGAL REQUEST asc:20,0

When I attempt copy my hard drive content to USB hard drive, I have it 
error in logs:
Nov 16 15:39:29 lissyara kernel: (da4:umass-sim1:1:0:0): SYNCHRONIZE 
CACHE(10). CDB: 35 0 0 0 0 0 0 0 0 0
Nov 16 15:39:29 lissyara kernel: (da4:umass-sim1:1:0:0): CAM Status: 
SCSI Status Error
Nov 16 15:39:29 lissyara kernel: (da4:umass-sim1:1:0:0): SCSI Status: 
Check Condition
Nov 16 15:39:29 lissyara kernel: (da4:umass-sim1:1:0:0): ILLEGAL REQUEST 
asc:20,0
Nov 16 15:39:29 lissyara kernel: (da4:umass-sim1:1:0:0): Invalid command 
operation code
Nov 16 15:39:29 lissyara kernel: (da4:umass-sim1:1:0:0): Unretryable error

And, through 2-3 minutes - my system is freeze.
I try it with 3 computers (all - CURRENT, 2 - amd64, 1 - x32)
I try another USB рввю It not help.
All will be have similar behavior (neither not complete copy)

lissyara# mount | grep ootFS
rootFS on / (zfs, local)
tmpRootFS on /tmpRootFS (zfs, local)
lissyara#

da4 at umass-sim1 bus 1 scbus4 target 0 lun 0
da4: <Maxtor 6 N040T0 1680> Fixed Direct Access SCSI-2 device
da4: 40.000MB/s transfers
da4: 38166MB (78165360 512 byte sectors: 255H 63S/T 4865C)

lissyara# uname -a
FreeBSD lissyara.moskb.local 9.0-CURRENT FreeBSD 9.0-CURRENT #0 r199307: 
Mon Nov 16 08:56:21 MSK 2009     
root_at_lissyara.moskb.local:/usr/obj/usr/src/sys/GENERIC  amd64

lissyara# zfs list
NAME          USED  AVAIL  REFER  MOUNTPOINT
rootFS       33,4G   195G  32,4G  none
rootFS/swap     1G   196G   137M  -
tmpRootFS    1,20G  35,5G  1,20G  /tmpRootFS
lissyara#