server crashes/freezes after other players connect

[Hotelmariofan]

Title: server crashes/freezes after other players connect

Version: 3.1.2

OS: Windows Vista Home premium 64bit

Java Version: 1.7.0_11-b21

Description of Problem:

I run a server and now all of the sudden, about every 30 minutes, all players will get kicked and receive a "Internal exception: java.net.SocketException: Connection reset", error. What's weird is that after everyone left out of frustration, I played for about 5 hours straight with no problem. When other players connect, after about 45 minutes, the server freezes and every is kicked and receives that message. The really weird thing is that it's like the server doesn't know it has crashed because there is no errors in the cmd. I can still type list, and it will show the players that were online before it crashed as if it had never crashed. Does anyone have idea why this may be? Thanks in advanced.

Error Messages:

Internal exception: java.net.SocketException: Connection reset

Error Log: