Why boot manger displays '#' symbol when I press buttons and doesn't boot?

[Yuri]

In an attempt to install FreeBSD I wrote /boot/boot0 on the harddrive 
which already has Windows on it plus free space.

Commands 'fdisk -B -b /boot/boot0 /dev/ad4' output ended with these 
messages:
Should we write new partition table? [n] y
fdisk: Class not found

After this when I boot from this HD it displays the usual:
F1 Win
F2
F3
F4 FreeBSD
...

But when I press any button it just prints the character '#' and does 
nothing.
If I don't type anything '#' characters appear by itself after some time 
and again nothing happens.

I suspect that fdisk message 'Class not found' is related.
What should I do to make FreeBSD boot manager to work?

Yuri