kernel panic on cdrom boot dragonfly v1.4.4

[rmkml]

Hi,
on my new hardware,
if I start with cdrom dragonfly v1.4.4 [boot default]
kernel panic :
 ad0: READ command timeout tag=0 serv=0 - resetting
 ata0: resetting devices .. instruction pointer = 0x8:0xc018a688
 stack pointer = 0x10:0xc201fcc8
 frame pointer = 0x10:0xc201fd14
 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 i386 without pb
Regards
Rmkml