I have experienced a bridged networking issue in VirutalBox 3.0.4 with Vista as host and Ubuntu 8.10 as guest.
My networking is installed as following:
A TP-LINK WR340G router configured with DHCP on; Vista Host system linked to this router and can get IP automatically; Ubuntu 8.04 refreshly installed in VirtulBox 3.0.4.
After I installed VirtualBox Addition, guest networking seemed hard to get IP from router. Somestimes it could get a IP. In most time, the networking configuration said that “the link was disconnected”.
I searched and someone said that change guest’s network card to “Intel PRO/1000 MT Desktop” might solve the problem. I tried it and successed.
If you have this problem, try to change your guest’s card type.