Can't Access Server

Minecraft was just updated to 1.3.1, so this may somehow be the cause of the problem. On 1.2.5, when I try to get on the server it says, "Failed to Connect: Bad Login." So I assumed it was updated to 1.3.1, but when I tried that, it said, "Internal exception: java.net.SocketException: Connection Reset." I was just wondering why this might be happening. Thank you.