Were you able to recover your photos? If so, how?
Also, some observations about how you reported your issue:
1) Were your photos still visible on your camera? I.e., was the card in fact the problem?
2) Did you try another USB port/another computer? USB ports have a nasty way of shutting down/misbehaving without letting you know. You can mitigate this by making sure that you remove the panel showing your camera's directory on your desktop and then (if you're using windows), use the "Safely Remove Hardware" button on your task bar -- before turning your camera off or removing the USB cable. Incidentally, I always turn my camera off before plugging in the USB cable.
3) If #1 is true, did you try to use a flash card reader instead of camera-computer USB connection?