Ubuntu Networking :: Can't Ping Localhost When Not Connected To Network

I'm having trouble pinging localhost, specifically, pinging localhost when I'm not connected to a network. When I try it keeps telling me the operation is not permitted:

Code:

matt@mubuntu:~$ ping localhost
PING localhost (127.0.0.1) 56(84) bytes of data.
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted

if I connect to the network, start pinging then disconnect it continues pinging. Google seems to think it could be something to do with my iptables setup:

Code:

matt@mubuntu:~$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

[code]....

When not connected to network

Code:

matt@mubuntu:~$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo

But as far as I can tell there isn't anything in there which would stop me connecting to the localhost (I also can't connect to my local apache instance when offline)... (It's worth mentioning that a couple of weeks ago I had the pc setup to share it's internet connection with a laptop, ala this guide, however I've since disabled the iptables rules and disabled ip forwarding.)