NAV Service down,any reason?

Log Name: Application
Source: MicrosoftDynamicsNAVServer
Date: 15/12/2011 3:19:16 AM
Event ID: 0
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: SERVERNAME.SHIPS.AD
Description:
Service:
The service MicrosoftDynamicsNavServer$NAVSCTINC failed to start. This could be caused by a configuration error. Detailed error information:System.ServiceModel.AddressAlreadyInUseException: The TransportManager failed to listen on the supplied URI using the NetTcpPortSharing service: the service failed to listen.
at System.ServiceModel.Channels.SharedConnectionListener.SharedListenerProxy.Register()
at System.ServiceModel.Channels.SharedConnectionListener.SharedListenerProxy.Open(Boolean isReconnecting)
at System.ServiceModel.Channels.SharedConnectionListener.StartListen(Boolean isReconnecting)
at System.ServiceModel.Channels.SharedConnectionListener..ctor(BaseUriWithWildcard baseAddress, Int32 queueId, Guid token, OnDuplicatedViaDelegate onDuplicatedViaCallback)
at System.ServiceModel.Channels.SharedTcpTransportManager.OnOpenInternal(Int32 queueId, Guid token)
at System.ServiceModel.Channels.SharedTcpTransportManager.OnOpen()
at System.ServiceModel.Channels.TransportManager.Open(TransportChannelListener channelListener)
at System.ServiceModel.Channels.TransportManagerContainer.Open(SelectTransportManagersCallback selectTransportManagerCallback)
at System.ServiceModel.Channels.TransportChannelListener.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.ConnectionOrientedTransportChannelListener.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.TcpChannelListener`2.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.Channels.ReliableChannelListenerBase`1.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at Microsoft.Dynamics.Nav.Types.Channels.ChunkingChannelListener.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.Dispatcher.ChannelDispatcher.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open()
at Microsoft.Dynamics.Nav.WindowsServices.NavServiceBase.OnStart(String[] args).
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"&gt;
<System>
<Provider Name="MicrosoftDynamicsNAVServer" />
<EventID Qualifiers="0">0</EventID>
<Level>2</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2011-12-15T11:19:16.000000000Z" />
<EventRecordID>5923</EventRecordID>
<Channel>Application</Channel>
<Computer>SERVERNAME.SHIPS.AD</Computer>
<Security />
</System>
<EventData>
<Data>Service:
The service MicrosoftDynamicsNavServer$NAVSCTINC failed to start. This could be caused by a configuration error. Detailed error information:System.ServiceModel.AddressAlreadyInUseException: The TransportManager failed to listen on the supplied URI using the NetTcpPortSharing service: the service failed to listen.
at System.ServiceModel.Channels.SharedConnectionListener.SharedListenerProxy.Register()
at System.ServiceModel.Channels.SharedConnectionListener.SharedListenerProxy.Open(Boolean isReconnecting)
at System.ServiceModel.Channels.SharedConnectionListener.StartListen(Boolean isReconnecting)
at System.ServiceModel.Channels.SharedConnectionListener..ctor(BaseUriWithWildcard baseAddress, Int32 queueId, Guid token, OnDuplicatedViaDelegate onDuplicatedViaCallback)
at System.ServiceModel.Channels.SharedTcpTransportManager.OnOpenInternal(Int32 queueId, Guid token)
at System.ServiceModel.Channels.SharedTcpTransportManager.OnOpen()
at System.ServiceModel.Channels.TransportManager.Open(TransportChannelListener channelListener)
at System.ServiceModel.Channels.TransportManagerContainer.Open(SelectTransportManagersCallback selectTransportManagerCallback)
at System.ServiceModel.Channels.TransportChannelListener.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.ConnectionOrientedTransportChannelListener.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.TcpChannelListener`2.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.Channels.ReliableChannelListenerBase`1.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at Microsoft.Dynamics.Nav.Types.Channels.ChunkingChannelListener.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.Dispatcher.ChannelDispatcher.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
at System.ServiceModel.Channels.CommunicationObject.Open()
at Microsoft.Dynamics.Nav.WindowsServices.NavServiceBase.OnStart(String[] args).</Data>
</EventData>
</Event>