I have been using Virtualbox for a long time, but never before I encountered this issue with this software. Basically my virtualized Windows 7 doesn't connect to the internet, it says that there is no connection. I tried to cycle through the different emulated network adapters (I am using NAT) but couldn't find a fix for it.
Any idea?
Under Devices, select network adapters and change the adapter type to 'bridged', this should solved the issue with no internet connection. The NAT adapter I've noticed sometimes fails for people, while bridged mode is always a reliable fallback. Virtualbox has a section on what the different modes and options for them here:
http://www.virtualbox.org/manual/ch06.html
Be careful, the bridged mode send packets through your host system, but bypasses your networking stack.