All I did was go into the settings of each of my virtual boxes (ubuntu and xp), I disabled the Network adapter, then I was able to start the machines when network was disabled. I shut them down, then enabled network, and they magically started working. I'm running Virtual Box 3.2.8 r64453 on Win 7 as the host (sorry linux brothers and sisters) and I'm running Ubuntu 10.04, and Win XP virtuals. I think this happened because I just updated the Win 7 host, and it updated the RealTek gigabit network hardware. I also have my Ubuntu box setup to auto start when Win 7 boots...though I have yet to test if that still works. If I don't reply again, then it worked...I'll reboot right now. Cheers!
Отсюда.