I re-installed WSUS a few months ago on a new server as part of a server hardware refresh. It is functioning normally downloading, authorizing and supplying patches to workstations.

System Specification:

• HP DL360 G5
• Quad 2.5 Zeon
• 6GB RAM
• Not Virtualized
• WSUS 3.2.7600.3226
• SQL 2005 Express
• Windows 2003 R2 SP2
• WSS SSL Enabled

Every six hours five events are logged to the Application Event Log:

Source                         | Category     | ID    | Description
--------------------------------------------------------------------------------------
Windows Server Update Services | Web Services | 12052 | The DSS Authentication Web Service is not working.
Windows Server Update Services | Web Services | 12042 | The SimpleAuth Web Service is not working
Windows Server Update Services | Web Services | 12022 | The Client Web Service is not working
Windows Server Update Services | Web Services | 12032 | The Server Synchronization Web Service is not working
Windows Server Update Services | Web Services | 12012 | The API Remoting Web Service is not working

In addition the following .NET Stack Trace is logged in C:\Program Files\Update Services\LogFiles\SoftwareDistribution.log each stack trace is identical except for the names of the services:

2009-11-27 11:56:52.757 UTC Error	WsusService.10	HmtWebServices.CheckApiRemotingWebService	ApiRemoting WebService WebException:System.Net.WebException: The request failed with HTTP status 403: Forbidden.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at Microsoft.UpdateServices.Internal.ApiRemoting.Ping(Int32 pingLevel)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.HmtWebServices.CheckApiRemotingWebService(EventLoggingType type, HealthEventLogger logger)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.HmtWebServices.CheckApiRemotingWebService(EventLoggingType type, HealthEventLogger logger)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.HealthMonitoringTasks.ExecuteSubtask(HealthMonitoringSubtask subtask, EventLoggingType type, HealthEventLogger logger)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.HmtWebServices.Execute(EventLoggingType type)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.HealthMonitoringTasks.Execute(EventLoggingType type)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.HealthMonitoringThreadManager.Execute(Boolean waitIfNecessary, EventLoggingType loggingType)
   at Microsoft.UpdateServices.Internal.HealthMonitoring.RemotingChannel.PrivateLogEvents()
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg, Int32 methodPtr, Boolean fExecuteInContext)
   at System.Runtime.Remoting.Messaging.ServerObjectTerminatorSink.SyncProcessMessage(IMessage reqMsg)
   at System.Runtime.Remoting.Lifetime.LeaseSink.SyncProcessMessage(IMessage msg)
   at System.Runtime.Remoting.Messaging.ServerContextTerminatorSink.SyncProcessMessage(IMessage reqMsg)
   at System.Runtime.Remoting.Channels.CrossContextChannel.SyncProcessMessageCallback(Object[] args)
   at System.Runtime.Remoting.Channels.ChannelServices.DispatchMessage(IServerChannelSinkStack sinkStack, IMessage msg, IMessage& replyMsg)
   at System.Runtime.Remoting.Channels.SoapServerFormatterSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)
   at System.Runtime.Remoting.Channels.BinaryServerFormatterSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)
   at System.Runtime.Remoting.Channels.Ipc.IpcServerTransportSink.ServiceRequest(Object state)
   at System.Runtime.Remoting.Channels.SocketHandler.ProcessRequestNow()
   at System.Runtime.Remoting.Channels.SocketHandler.BeginReadMessageCallback(IAsyncResult ar)
   at System.Runtime.Remoting.Channels.Ipc.IpcPort.AsyncFSCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOverlapped)
   at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)

So far I have tried the following:

• Ensuring the settings were accurate as per TechNet.
• Checked that there was a suitable binding to 127.0.0.1 binding in IIS.
• Gone through and checked the settings in IIS as per TechNet.

I have discovered that you can run the command wsusutil checkhealth to force the healt check to run, wsusutil can be found in C:\Program Files\Update Services\Tools. When this executese it will tell you to check the application log.