Error after upgraded to 5.0.18

[maumar]

i have just upgraded to:
zcs-5.0.18_GA_3011.DEBIAN4.0.20090707170635
and now i get this error every imap connection:

2009-07-31 08:44:35,614 INFO  [ImapServer-142] [] ProtocolHandler - Exception occurred while handling connection                                              
java.net.SocketException: Connection reset                                                                                                                    
        at java.net.SocketInputStream.read(SocketInputStream.java:168)                                                                                        
        at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:235)
        at com.zimbra.cs.tcpserver.TcpServerInputStream.readLine(TcpServerInputStream.java:73)
        at com.zimbra.cs.imap.TcpImapRequest.continuation(TcpImapRequest.java:52)
        at com.zimbra.cs.imap.TcpImapHandler.processCommand(TcpImapHandler.java:106)
        at com.zimbra.cs.tcpserver.ProtocolHandler.processConnection(ProtocolHandler.java:160)
        at com.zimbra.cs.tcpserver.ProtocolHandler.run(ProtocolHandler.java:128)
        at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:595)

i have no clue