Chris as a wildcard.
I lost all connectivity (wired and wireless) a few days after setting up Oracle VirtualBox on my Laptop. Eventually I tracked down the network protocols for it and removed them and all was well (including network connectivity for VirtualBox).
I've been experimenting to see if I can mix Windows and Ubuntu apps at the same time with VirtualBox although I've put that aside for the moment while follow up some other interests.
http://www.virtualbox.org/
Bob