Recurring Actipro exception in VS 2010 editor

I am rather new to Actipro and XAML, though I've been doing similar work for a long time.  I am developing a spin-off of an existing product and don't know where to look to correct a frequently recurring exception I get in the VS 2010 editor.  I can "reload" (sometimes a couple time) and then it looks right in the editor for a few minutes, then the exception occurs again.  I am able to edit the XAML directly and the compiled application works as I intended.  This is just a development environment issue.

I can't send the whole project, but if someone can decode this down to something like "look at your ____ controls" or some such, that would go a long way.  The exceptions below are copied directly from what I see in the design window.  Thanks in advance for any help!

System.ArgumentException
GenericArguments[0], 'ActiproSoftware.Windows.Themes.EditorsThemeCatalog', on 'ActiproSoftware.Windows.Themes.ThemeCatalogRegistrarBase'1[T]' violates the constraint of type 'T'.
at System.RuntimeType.ValidateGenericArguments(MemberInfo definition, RuntimeType[] genericArguments, Exception e)
at System.RuntimeType.MakeGenericType(Type[] instantiation)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUtil.GetRuntimeType(Type type)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkType.TryGetRuntimeType()
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUtil.EnsureRuntimeType(Type type)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkProvider.GetRuntimeType(Type reflectionType)
at MS.Internal.Package.VSIsolationProviderService.RemoteReferenceProxy.VsReflectionResolver.GetRuntimeType(Type reflectionType)
at Microsoft.Windows.Design.Metadata.ReflectionMetadataContext.CachingReflectionResolver.GetRuntimeType(Type reflectionType)
at Microsoft.Windows.Design.Metadata.ReflectionMetadataContext.Microsoft.Windows.Design.Metadata.IReflectionResolver.GetRuntimeType(Type reflectionType)
at MS.Internal.Metadata.ClrType.get_RuntimeMember()
at MS.Internal.Metadata.ClrMember'1.Microsoft.Windows.Design.Metadata.Reflection.IReflectionMember.get_MemberInfo()
at MS.Internal.Metadata.ClrType.Equals(Object obj)
at System.Collections.Generic.ObjectEqualityComparer'1.Equals(T x, T y)
at System.Collections.Generic.Dictionary'2.FindEntry(TKey key)
at Microsoft.Windows.Design.Metadata.Xaml.XamlExtensionImplementations.<>c__DisplayClass5.<FindAttachableProperties>b__4(ITypeMetadata walkType)
at MS.Internal.Design.Metadata.Xaml.XamlType.<GetAllAttachableProperties>d__7.MoveNext()
at MS.Internal.Design.Metadata.Xaml.XamlType.<FindAttachableProperties>d__0.MoveNext()
at Microsoft.Windows.Design.Metadata.Xaml.XamlExtensionImplementations.<FindAttachableProperties>d__7.MoveNext()
at MS.Internal.VirtualModel.VirtualModelPropertyCollection.<GetUncachedProperties>d__0.MoveNext()
at System.Linq.Buffer'1..ctor(IEnumerable'1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable'1 source)
at MS.Internal.VirtualModel.VirtualModelPropertyCollection.GetEnumerator()
at MS.Internal.VirtualModel.VirtualModelUtilities.WrapProperties(IVirtualModelItem item)
at MS.Internal.VirtualModel.VirtualModelItem.System.ComponentModel.ICustomTypeDescriptor.GetProperties()
at System.ComponentModel.TypeDescriptor.MergedTypeDescriptor.System.ComponentModel.ICustomTypeDescriptor.GetProperties()
at System.ComponentModel.TypeDescriptor.GetPropertiesImpl(Object component, Attribute[] attributes, Boolean noCustomTypeDesc, Boolean noAttributes)
at System.Windows.PropertyPath.ResolvePropertyName(String name, Object item, Type ownerType, Object context, Boolean throwOnError)
at MS.Internal.Data.PropertyPathWorker.GetInfo(Int32 k, Object item, SourceValueState& svs)
at MS.Internal.Data.PropertyPathWorker.ReplaceItem(Int32 k, Object newO, Object parent)
at MS.Internal.Data.PropertyPathWorker.UpdateSourceValueState(Int32 k, ICollectionView collectionView, Object newValue, Boolean isASubPropertyChange)
at MS.Internal.Data.ClrBindingWorker.AttachDataItem()
at System.Windows.Data.BindingExpression.Activate(Object item)
at System.Windows.Data.BindingExpression.AttachToContext(AttachAttempt attempt)
at System.Windows.Data.BindingExpression.AttachOverride(DependencyObject target, DependencyProperty dp)
at System.Windows.Data.MultiBindingExpression.AttachBindingExpression(Int32 i, Boolean replaceExisting)
at System.Windows.Data.MultiBindingExpression.AttachOverride(DependencyObject d, DependencyProperty dp)
at System.Windows.Data.BindingExpressionBase.Attach(DependencyObject target, DependencyProperty dp)
at System.Windows.Data.BindingExpressionBase.OnAttach(DependencyObject d, DependencyProperty dp)
at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
at System.Windows.Data.BindingOperations.SetBinding(DependencyObject target, DependencyProperty dp, BindingBase binding)
at MS.Internal.GridControl.GridColumnAdornerBase..ctor(ModelItem gridItem, ModelItem columnItem)
at MS.Internal.GridControl.GridColumnSelectAdorner..ctor(ModelItem grid, ModelItem column)
at MS.Internal.GridControl.GridDesigner.EnsureColumnAdorners(ModelItem columnDefModel, Boolean withHandle)
at MS.Internal.GridControl.GridDesigner.EnsureAllColumnAdorners()
at MS.Internal.GridControl.GridDesigner.InitGridDesigner()
at MS.Internal.GridControl.GridDesigner.GetDesigner(ModelItem gridItem)
at MS.Internal.GridControl.AlwaysVisibleGridAdornerProvider.Activate(ModelItem item)
at Microsoft.Windows.Design.Interaction.AdornerProvider.InvokeActivate(EditingContext context, ModelItem item)
at MS.Internal.Features.AdornerProviderFeatureConnector.FeatureProvidersAdded(ModelItem item, IEnumerable'1 extensions)
at Microsoft.Windows.Design.Policies.PolicyDrivenFeatureConnector'1.UpdateFeatureProviders()
at MS.Internal.Features.PolicyDrivenToolFeatureConnector'1.UpdateCurrentTool(Tool newTool)
at MS.Internal.Features.PolicyDrivenToolFeatureConnector'1.<.ctor>b__0(Tool newTool)
at Microsoft.Windows.Design.ContextItemManager.SubscribeProxy'1.SubscribeContext(ContextItem item)
at Microsoft.Windows.Design.SubscribeContextCallback.Invoke(ContextItem item)
at Microsoft.Windows.Design.EditingContext.DefaultContextItemManager.OnItemChanged(ContextItem item)
at Microsoft.Windows.Design.EditingContext.DefaultContextItemManager.SetValue(ContextItem value)
at MS.Internal.Host.ToolSubsystem.ActivateTool(ToolFactory toolFactory)
at MS.Internal.Host.ToolSubsystem..ctor(EditingContext editingContext, DesignerContext designerContext)
at MS.Internal.Host.Designer.Load()
at MS.Internal.Designer.VSDesigner.Load()
at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.Load()
at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedDesignerFactory.Load(IsolatedView view)
at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view)
at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view)
at MS.Internal.Host.Isolation.IsolatedDesigner.Load()
at MS.Internal.Designer.DesignerPane.LoadDesignerView(Boolean isReload)

System.TypeLoadException
GenericArguments[0], 'ActiproSoftware.Windows.Themes.EditorsThemeCatalog', on 'ActiproSoftware.Windows.Themes.ThemeCatalogRegistrarBase'1[T]' violates the constraint of type parameter 'T'.
at System.RuntimeTypeHandle.Instantiate(RuntimeTypeHandle handle, IntPtr* pInst, Int32 numGenericArgs, ObjectHandleOnStack type)
at System.RuntimeTypeHandle.Instantiate(Type[] inst)
at System.RuntimeType.MakeGenericType(Type[] instantiation)