when i connect my mac in server i'm disconnect. Why ? 1.6.1 (I'm french)

Client> java.net.SocketException: Connection reset
Client>at java.net.SocketInputStream.read(SocketInputStream.java:168)
Client>at java.io.FilterInputStream.read(FilterInputStream.java:116)
Client>at org.bouncycastle.crypto.io.CipherInputStream.nextChunk(Unknown Source)
Client>at org.bouncycastle.crypto.io.CipherInputStream.read(Unknown Source)
Client>at java.io.DataInputStream.readFully(DataInputStream.java:178)
Client>at ek.a(SourceFile:84)
Client>at ex.a(SourceFile:206)
Client>at cn.i(SourceFile:248)
Client>at cn.c(SourceFile:16)
Client>at co.run(SourceFile:93)
Client> 2013-07-02 11:49:30 [CLIENT] [INFO] Stopping!
Client> 
Client> SoundSystem shutting down..