So Windows 7 uses the hosts file like nigh on every other OS and, thanks to lots and lots of messing around with servers, my hosts file was messed up. All I wanted to do was set up localhost to point to 127.0.0.1!
I use Boxer but every time I edited the file and tried to save it it wouldn't let me, telling me that Access was denied!
I guessed that this was down to not running Boxer as an administrator so instead of using the nice shortcut I usually use to launch Boxer I found it in the Start menu and right-clicked it as chose "Run as administrator", this let me save properly and now localhost points to the IP address 127.0.0.1! Yay!