Null Pointer Exception randomly

My server keeps randomly kicking all users with a "Read time out" for unknown reasons, I've never been able to catch it with an error at the time, until the past day, and it's always this:

Code:

2012-03-19 19:43:27 [SEVERE] java.lang.NullPointerException
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:34)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.NetLoginHandler.a(NetLoginHandler.java:191)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.Packet254GetInfo.handle(SourceFile:16)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.NetworkManager.b(NetworkManager.java:231)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.NetLoginHandler.a(NetLoginHandler.java:52)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:61)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:543)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:441)
2012-03-19 19:43:27 [SEVERE]    at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)

No specific player initiated actions seem to be causing it, if I wait long enough once in a blue moon it'll just boot me with a read time out if I'm the only one on, just standing around. I've been unable to isolate a plugin or other item causing this error. Any help would be greatly appreciated it's getting really frustrating!