virtualbox.org

I have two ubuntu guests in my 4.3.10 virtualbox both ubuntu 12.04 and on one the internet stopped working while the other works fine.
I use NAT.

So it stopped working two weeks ago.
How do i fix the internet on the one where its not working?

I'm willing to bet everything I own, and will ever own (including my first-born son), that if you have two identical guests, the problem is not with VirtualBox. Take a close look at your guest configurations...

Any idea what i should be looking for?

NAT make easy to use a virtual machine because:

it does not require to configure guest network parameters (the router act as DHCP server and give all the needed information to the guest)
it guarantees that the VM can be executed in any network environment without breaking the existing network.

If i dont have to configure anything and i didnt do anything with the internet, why did it stop working. It tells me it connects but it can't load a single webpage.
So I have a Bio-linux package build on ubuntu 12.04 which doesnt work and a qiime package build on 12.04 that does work. They both used to work.

I have no clue what to do. I can't find any information what might be goign wrong, I have been looking for several hours on this forum and elsewhere.

I'm not a Linux expert by no means, but I've seen reports about "/etc/resolv.conf" causing problems. Search the forums for this. Maybe an expert could chime in...