I recently had my computer crash hard while my bitnami Ruby on Rails stack was running in VirtualBox. When I tried to start up the virtual machine again it said "waiting for network configuration" and hung for about a minute. Then it said "Continuing to wait for network configuration for another 60 seconds." Once the system started I noticed it didn't have a ip address assigned and if I typed ifconfig I only got the loopback interface (no network interface to speak of). Luckily, there was a simple fix for this, but it took me a little while to figure out so I figured I'd share it here in hopes others with the same problem will wind up here and I can save you some time.
First type ifconfig and see what comes up. For me I only had one interface and it was the lo interface. If you are seeing your network interface you probably want to try something else as this is probably not your issue. I advise going to the Bitnami or VirtualBox sites and looking at their FAQ.
The first thing recommended on the Bitnami site was to run /etc/init.d/networking force-reload which resulted in an error "cannot find device eth0."
Another informative piece of information was the "Ignoring unknown interface eth2″ message. So as it turns out VirtualBox moved my network interface from eth0 to eth2. I have no idea why this happened, but it's an easy fix.
First type in ifconfig -a to see your interfaces
As you can see here I have an eth2 that is not connected, lo and that is it. No eth0. So now we just need to add it in. to do that simply edit /etc/network/interfaces in your favorite text editor find the part where it mentions the wrong interface and change it to the correct interface.
After that all you need to do is reload the interface and it should work. You can reboot the whole system or do a force-reload like this /etc/init.d/networking force-reload
After that I was back online. I've rebooted a couple times since then and it seems to be working great. Apparently my new default network interface is eth2. Couldn't tell you why it changed when my computer froze, but it all works fine now that I updated the config file. Easy fix.