Hi,
I have several different versions of DNN.
Sometimes with no any change in Modules or...  I have this error,
"An item with the same key has already been added"
and when i was copy a dll to bin(restart app) The error is resolved.

I don't know what's error for?

<LogProperty>
        <PropertyName>Method</PropertyName>
        <PropertyValue>System.ThrowHelper.ThrowArgumentException</PropertyValue>
    </LogProperty>
    <LogProperty>
        <PropertyName>StackTrace</PropertyName>
        <PropertyValue />
    </LogProperty>
    <LogProperty>
        <PropertyName>Message</PropertyName>
        <PropertyValue>System.Exception: Unhandled Error:  ---&gt; System.TypeInitializationException: The type initializer for 'DotNetNuke.Entities.Users.UserController' threw an exception. ---&gt; System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---&gt; System.ArgumentException: An item with the same key has already been added.     at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)     at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)     at System.Collections.ObjectModel.KeyedCollection`2.AddKey(TKey key, TItem item)     at System.Collections.ObjectModel.KeyedCollection`2.InsertItem(Int32 index, TItem item)     at System.Collections.ObjectModel.Collection`1.Add(T item)     at DotNetNuke.ComponentModel.SimpleContainer.RegisterComponentInstance(String name, Type contractType, Object instance)     at DotNetNuke.ComponentModel.AbstractContainer.RegisterComponentInstance[TContract](Object instance)     at DotNetNuke.ComponentModel.ComponentFactory.RegisterComponentInstance[TContract](Object instance)     at DotNetNuke.Security.Membership.AspNetMembershipProvider..ctor()     --- End of inner exception stack trace ---     at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean&amp; canBeCached, RuntimeMethodHandle&amp; ctor, Boolean&amp; bNeedSecurityCheck)     at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache)     at System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache)     at System.Activator.CreateInstance(Type type, Boolean nonPublic)     at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)     at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)     at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)     at System.Type.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args, CultureInfo culture)     at DotNetNuke.Framework.Reflection.CreateInstance(Type Type)     at DotNetNuke.ComponentModel.SingletonComponentBuilder.CreateInstance()     at DotNetNuke.ComponentModel.SingletonComponentBuilder.BuildComponent()     at DotNetNuke.ComponentModel.SimpleContainer.GetComponent(IComponentBuilder builder)     at DotNetNuke.ComponentModel.SimpleContainer.GetComponent(Type contractType)     at DotNetNuke.ComponentModel.AbstractContainer.GetComponent[TContract]()     at DotNetNuke.ComponentModel.ComponentFactory.GetComponent[TContract]()     at DotNetNuke.Security.Membership.MembershipProvider.Instance()     at DotNetNuke.Entities.Users.UserController..cctor()     --- End of inner exception stack trace ---     at DotNetNuke.Entities.Users.UserController.GetUserCountByPortal(Int32 portalId)     at DotNetNuke.Entities.Portals.PortalInfo.Fill(IDataReader dr)     at DotNetNuke.Common.Utilities.CBO.FillObjectFromReader(Object objObject, IDataReader dr)     at DotNetNuke.Common.Utilities.CBO.CreateObjectFromReader(Type objType, IDataReader dr, Boolean closeReader)     at DotNetNuke.Common.Utilities.CBO.FillListFromReader(Type objType, IDataReader dr, IList objList, Boolean closeReader)     at DotNetNuke.Common.Utilities.CBO.FillCollection(IDataReader dr, Type objType)     at DotNetNuke.Entities.Portals.PortalController.GetPortals()     at DotNetNuke.Common.Initialize.CacheMappedDirectory()     at DotNetNuke.Common.Initialize.InitializeApp(HttpApplication app)     at DotNetNuke.Common.Initialize.Init(HttpApplication app)     at DotNetNuke.HttpModules.RequestFilter.RequestFilterModule.FilterRequest(Object sender, EventArgs e)     at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()     at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)     --- End of inner exception stack trace ---</PropertyValue>
    </LogProperty>

No,