Can't work out which disk we are booting from

[Dragos]

Hi,

    I have installed freebsd 7.1 on a 8GB usb flash drive. Now, it seems 
that the freebsd loader is unable to identify the usb disk where is 
booting from(da0s1a).
 The loader runs fine from the stick but gets confused on the drive it 
runs from, and the kernel it's not loaded.

Here is what the loader prints out:
[...]
Bios drive A: is disk0
[...]
Can't work out which disk we are booting from.
Guessed BIOS device 0x80 not found by probes, defaulting to disk0:

can't load 'kernel'


I installed grub too and grub is loading the freebsd loader just fine, 
but the freebsd loader still get confused. Unfortunately I wasn't able 
to load the kernel (/boot/kernel/kernel) directly from grub.