I got this error today after an upgrade and google searched a lot. Turns out some one had encountered this error and had got the perfect fix: Nemethge’s Blog
I am not sure exactly why this works but it seems like just symlinking your /var/run with your /run seems to do the trick. Anyway you have him to thank for coming up with this solution. I can safely say it works (just tried it now). I have quoted the solution below just incase of deadlinks etc:
Note: This also solved the problem of my network settings not being found and Ubuntu waiting 60 secs before loading. So if your getting this problem then it could be related to the solution below however I have the same network problem on another network and that install of Ubuntu can find its network at startup despite the error message (can login remotely without having to restart the network for one). So this solution may not solve every case you get the network error message but it will in some cases.
It seems the move from /var/run to /run did not work during the upgrade process.
I fixed with this:
mv run _run
ln -s /run .