As soon as I press 'Login' it doesn't even take a millisecond before the 'An error has occured. Check you network blah blah' popup appears.

Is this global, or just me?

Happened to me a few days ago, but now it's working. Check back later or try some fix

Looks like Crysis 2 cannot create a socket on port 64100 through 64160. This will likely be fixed by rebooting, but I can't reboot so I will deal with this another way.