Right, let's try unplugging it from both ends.
Okay, the switch has lit up green. Windows is still refusing to see the friggin' cable! And I'd rather not restart this machine, as it's the one that I'm a) connected to the internet on; b) playing music from; and c) typing this on. Grumblegrumblegrumble...
Okay, what is up with this thing? It's even sending packets across! I can ping the laptop across this connection!
Ah sod it, restart.