WPF: Exception has been thrown by the target of an invocation on user's computer

I'm trying to run my WPF application on my user's computer, but upon startup it gives the following error:

An unhandled exception occurred

Inner exception: Exception has been thrown by the target of an invocation.

Stack trace:

at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)

   at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)

   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)

   at System.Activator.CreateInstance(Type type, Boolean nonPublic)

   at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)

   at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)

   at System.Activator.CreateInstance(Type type, Object[] args)

   at System.Xaml.Schema.SafeReflectionInvoker.CreateInstanceCritical(Type type, Object[] arguments)

   at System.Xaml.Schema.XamlTypeInvoker.CreateInstance(Object[] arguments)

   at MS.Internal.Xaml.Runtime.ClrObjectRuntime.CreateInstance(XamlType xamlType, Object[] args)

   at System.Xaml.XamlObjectWriter.Logic_CreateAndAssignToParentStart(ObjectWriterContext ctx)

   at System.Xaml.XamlObjectWriter.WriteStartMember(XamlMember property)

   at System.Windows.Markup.WpfXamlLoader.TransformNodes(XamlReader xamlReader, XamlObjectWriter xamlWriter, Boolean onlyLoadOneNode, Boolean skipJournaledProperties, Boolean shouldPassLineNumberInfo, IXamlLineInfo xamlLineInfo, IXamlLineInfoConsumer xamlLineInfoConsumer, XamlContextStack`1 stack, IStyleConnector styleConnector)

   at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri)

   at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri)

   at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)

   at System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc)

   at System.Windows.Application.LoadComponent(Uri resourceLocator, Boolean bSkipJournaledProperties)

   at System.Windows.Application.DoStartup()

   at System.Windows.Application.<.ctor>b__1(Object unused)

   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)

   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

Why would this happen?  I've got no idea which line of code causes the error.  Everything works on my development computer.