kernel panic on default cdrom boot dragonflybsd v1.6.0

[rmkml <rmkml@xxxxxxx>]

Hi,
on my hardware (dual core amd64x2),
if I start with cdrom dragonfly v1.6.0 [boot default]
kernel panic :
 ...
 ad0: READ command timeout tag=0 serv=0 - resetting
 ata0: resetting devices .. instruction pointer = 0x8:0xc018c06c
 stack pointer = 0x10:0xc22bfcc8
 frame pointer = 0x10:0xc22bfd14
 code segment  = base 0x0, limit 0xfffff, type 0x1b
               = DPL 0, pres 1, def32 1, gran 1
 processor eflags = interrupt enabled, IOPL = 0
 current process = idle
 current thread = pri 14
 kernel: type 30 trap, code=0
 stopped at ata_reset+0x31: jmp ata_reset+0x36
 db>
anyone help me ? (but keyboard is locked)
hardware conf: amd x2, ide 180Go
boot and install on netbsd3/freebsd61/openbsd39 without pb
same old pb dfly144 : 
http://www.mail-archive.com/kernel@xxxxxxxxxxxxxxxxxxxxxxx/msg01241.html
Regards
Rmkml