CRM trying re-create 'Business Closure Calendar' calendar every minute - iis

Question

We are getting following error in event log because InternalOperationPlugin is trying to create 'Business Closure Calendar' in Calender entity almost every minute.
InternalOperationPlugin is a core system plugin which is registered on Stage 30 (non-customizable). Can anyone give an idea why core plugin is trying to create this record every minute.
We are on Roll up 8 and not in position to install latest.
Thanks in Advance
The Web Service plug-in failed in OrganizationId: 07ae1f6f-237f-e111-83c6-005056b41d30; SdkMessageProcessingStepId: 22ccbb1b-ea3e-db11-86a7-000a3a5473e8;
EntityName: calendar;
Stage: 30;
MessageName: RetrieveMultiple;
AssemblyName: Microsoft.Crm.Extensibility.InternalOperationPlugin, Microsoft.Crm.ObjectModel, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35;
ClassName: Microsoft.Crm.Extensibility.InternalOperationPlugin;
Exception: Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Web.Services.Protocols.LogicalMethodInfo.Invoke(Object target, Object[] values)
at Microsoft.Crm.Extensibility.InternalOperationPlugin.Execute(IServiceProvider serviceProvider)
at Microsoft.Crm.Extensibility.V5PluginProxyStep.ExecuteInternal(PipelineExecutionContext context)
at Microsoft.Crm.Extensibility.VersionedPluginProxyStepBase.Execute(PipelineExecutionContext context)
Inner Exception: System.ArgumentException: Item has already been added. Key in dictionary: '7fdf4980-237f-e111-83c6-005056b41d30' Key being added: '7fdf4980-237f-e111-83c6-005056b41d30'
at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add)
at Microsoft.Crm.ObjectModel.CalendarService.RetrieveMultiple(EntityExpression entityExpression, ExecutionContext context)
** Error from Event Log **
at VersionedPluginProxyStepBase.Execute(PipelineExecutionContext context)
at Pipeline.Execute(PipelineExecutionContext context)
at MessageProcessor.Execute(PipelineExecutionContext context)
at InternalMessageDispatcher.Execute(PipelineExecutionContext context)
at ExternalMessageDispatcher.ExecuteInternal(IInProcessOrganizationServiceFactory serviceFactory, IPlatformMessageDispatcherFactory dispatcherFactory, String messageName, String requestName, Int32 primaryObjectTypeCode, Int32 secondaryObjectTypeCode, ParameterCollection fields, CorrelationToken correlationToken, CallerOriginToken originToken, UserAuth userAuth, Guid callerId, Guid transactionContextId, Int32 invocationSource, Nullable`1 requestId, Version endpointVersion)
at OrganizationSdkServiceInternal.ExecuteRequest(OrganizationRequest request, CorrelationToken correlationToken, CallerOriginToken callerOriginToken, WebServiceType serviceType)
at OrganizationSdkServiceInternal.Execute(OrganizationRequest request, CorrelationToken correlationToken, CallerOriginToken callerOriginToken, WebServiceType serviceType)
at InprocessServiceProxy.ExecuteCore(OrganizationRequest request)
at SandboxSdkListener.Execute(SandboxCallInfo callInfo, SandboxSdkContext requestContext, String operation, Byte[] serializedRequest)
at
at SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)
at DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
at ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
at ImmutableDispatchRuntime.ProcessMessage31(MessageRpc& rpc)
at MessageRpc.Process(Boolean isOperationContextSet)
at ChannelHandler.DispatchAndReleasePump(RequestContext request, Boolean cleanThread, OperationContext currentOperationContext)
at ChannelHandler.HandleRequest(RequestContext request, OperationContext currentOperationContext)
at ChannelHandler.AsyncMessagePump(IAsyncResult result)
at AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at AsyncResult.Complete(Boolean completedSynchronously)
at TryReceiveAsyncResult.OnReceive(IAsyncResult result)
at AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at AsyncResult.Complete(Boolean completedSynchronously)
at ReceiveAsyncResult.OnReceiveComplete(Object state)
at SessionConnectionReader.OnAsyncReadComplete(Object state)
at AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at LazyAsyncResult.Complete(IntPtr userToken)
at NegotiateStream.ProcessFrameBody(Int32 readBytes, Byte[] buffer, Int32 offset, Int32 count, AsyncProtocolRequest asyncRequest)
at NegotiateStream.ReadCallback(AsyncProtocolRequest asyncRequest)
at FixedSizeReader.CheckCompletionBeforeNextRead(Int32 bytes)
at FixedSizeReader.ReadCallback(IAsyncResult transportResult)
at AsyncResult.Complete(Boolean completedSynchronously)
at ReadAsyncResult.OnAsyncReadComplete(Object state)
at SocketConnection.AsyncReadCallback(Boolean haveResult, Int32 error, Int32 bytesRead)
at IOCompletionThunk.UnhandledExceptionFrame(UInt32 error, UInt32 bytesRead, NativeOverlapped* nativeOverlapped)
at _IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)
Web Service Plug-in failed in SdkMessageProcessingStepId: {22CCBB1B-EA3E-DB11-86A7-000A3A5473E8}; EntityName: calendar; Stage: 30; MessageName: RetrieveMultiple; AssemblyName: Microsoft.Crm.Extensibility.InternalOperationPlugin, Microsoft.Crm.ObjectModel, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35; ClassName: Microsoft.Crm.Extensibility.InternalOperationPlugin; Exception: Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Web.Services.Protocols.LogicalMethodInfo.Invoke(Object target, Object[] values)
at Microsoft.Crm.Extensibility.InternalOperationPlugin.Execute(IServiceProvider serviceProvider)
at Microsoft.Crm.Extensibility.V5PluginProxyStep.ExecuteInternal(PipelineExecutionContext context)
at Microsoft.Crm.Extensibility.VersionedPluginProxyStepBase.Execute(PipelineExecutionContext context)
Inner Exception: System.ArgumentException: Item has already been added. Key in dictionary: '7fdf4980-237f-e111-83c6-005056b41d30' Key being added: '7fdf4980-237f-e111-83c6-005056b41d30'
at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add)
at Microsoft.Crm.ObjectModel.CalendarService.RetrieveMultiple(EntityExpression entityExpression, ExecutionContext context)
.
UPDATE
I have already checked Calendar Entity. There is only one record with Id equals to '7fdf4980-237f-e111-83c6-005056b41d30'. Mpreover, I have searched whole database to find out if there is any other record using same Id.