BTX halted with a flashcard usb plugged

[User Patrice]

Hello

I m using a fresh new install of freebsd 6.0, on sata disk.

I have a btx halted error every time i boot with a usb flashcard plugged.

BTX loader 1.00 BTX version 1.01
Consoles Internal video/keyboard
Bios drive A: is disk0

int=0000000d	err=00000000	efl=00030002	eip=00002aca
eax=00000000	ebx=00000000	ecx=00000001	edx=00000001
esi=00000000	edi=00008609	ebp=00000000	esp=000003f6

cs=f000	ds=0000	es=f000	fs=0000	gs=0000	ss=9e3b

btx halted


I have tryed with 2 different usb:
1/ 
umass0: vendor 0x13fe USB Disk 2.0, rev 2.00/1.00 addr 2
da0 at umass0-sim0 bug 0 target 0 lun 0
da0: <USB DISK 2.0 PMAP> Removable Direct Access SCSI-0 Device
da0: 40.000MB/s Transfers
da0: 240MB (492544 512 byte/sectors: 64H 32S/T 240C)

2/
umass0: vendor 0x0457 USB Mass Storage Device, rev 2.00/1.00 addr 2
da0 at umass0-sim0 bug 0 target 0 lun 0
da0: <Ut161 USB2FlashStorage 0.00> Removable Direct Access SCSI-2 Device
da0: 40.000MB/s Transfers
da0: 480MB (983808 512 byte/sectors: 64H 32S/T 480C)


USB flash plugged: BTX Halted
USB flash unplugged: freebsd boot fine

Boot order: hd, then usb hd.