Closed Unassigned: System.ArgumentOutOfRangeException on Disconnect() [2389]

Version: __2013.4.7.0__

Hey everybody,

I am sporadically getting the following exception while trying to disconnect SftpClient.

__System.ArgumentOutOfRangeException__: Specified argument was out of the range of valid values.
Parameter name: length
at Renci.SshNet.Session.WaitHandle(WaitHandle waitHandle)
at Renci.SshNet.Channels.Channel.Close(Boolean wait)
at Renci.SshNet.Channels.ChannelSession.Close(Boolean wait)
at Renci.SshNet.Channels.Channel.Close()
at Renci.SshNet.Sftp.SubsystemSession.Disconnect()
at Renci.SshNet.SftpClient.OnDisconnecting()
at Renci.SshNet.BaseClient.__Disconnect()__

Code Snippet:
```
if (sftpClient.IsConnected)
sftpClient.Disconnect();
```

Any idea why ?
Comments: The reporter of this issue will upgrade to the latest version and reopen the issue if necessary.