VirtualBox: No network connectivity. Weird vboxnetflt.ko/vboxnetadp.ko behaviour

[O. Hartmann]

Running a FreeBSD 8.0-REL/amd64 box with a quad core CPU and 8 GB of ram 
I intended also to operate Windows XP_32 within VirtualBox.
So far, VirtualBox is up and running, as well as Windows XP. But I do 
not have network connectivity.

Befor going deeper into my config I will report some strange behaviour 
of needed kernel modules

vboxnetflt.ko
vboxnetadp.ko

Both are needed for networking on VirtualBox and they get loaded at 
startup vi /boot/loader.conf. But to have a working network, I have to 
unload and then reload them, since if they get loaded at startup, 
networking is broken in virtual box!

My FreeBSD-based config is simple. I have a bridged NIC (msk0), a tap0 
device which is member of the bridge. But follwoing setups known from 
Qemu with tap0 do not work. So far.
On Windows XP side I use as 'physical' device PCnet FAST III (doesn't 
matter whether it is II or III), 'Attached to' is 'Bridged adapter' and 
'Name' is either msk0 or tap0, where only mask0 shows activity.

My virtual box does have its own regular IP, so I tried setting the IP 
of Windows's adapter to this and after this attempt failed, I set it to 
the very same of the host. I never get a running network with this.

I also switched off (or making it transparent) the filtering facility 
(pf), but with no effect.

Has anybody similar trouble?

Thanks,

Oliver