Migrating to .Net 4: Null reference exceptions thrown when adding event in xaml

Question

At my place of work we've recently been upgrading our codebase from .Net 3.5 to .Net 4 (C#). Most issues encountered have been solved however this one I can't figure out. We initialise controls and pages through a mix of xaml and code behind (based on developer preference), however one page is throwing NullReferenceException when opened. Here is a snippet of code that is (one of many controls) throwing.

All the code throwing exceptions is inside a DataTemplate (I figured that might be relevant)

<TextBox x:Name="Values" Grid.Column="1" Grid.Row="0" Margin="5,2,5,2"
  Text="{Binding ElementName=Descriptions, Path=SelectedValue, UpdateSourceTrigger=PropertyChanged,
  Mode=TwoWay,        
  Converter={StaticResource EmptyConverter}}"
  GotFocus="Column_GotFocus"
  MinWidth="100"
  CharacterCasing="Upper"
  Visibility="{Binding Path=IsValueVisible, Converter={StaticResource VisibilityConverter}}" 
/>

Now in this, the line throwing is:

GotFocus="Column_GotFocus" 

Column_GotFocus is in the code behind file. A few more facts: we had no issues before the migration, the exception gets throws continuously, and there are three different events causing this issue.

The three events throwing are:

GotFocus="Column_GotFocus"
SelectionChanged="Descriptions_SelectionChanged"
Click="Search_Click"

Removing these fixes our problem completely, but obviously causes functional problems with the software. Does anyone have any idea what could be causing these issues?

EDIT:

Sorry, to clarify: The event handler is never called, the xaml event handler adding (GotFocus="Column_GotFocus" for example) seems to be where the exception is thrown.

The exception is:

System.NullReferenceException occurred
  Message=Object reference not set to an instance of an object.
  Source= <assembly/namespace>
  StackTrace:
       at <assembly/namespace>.<Class>.System.Windows.Markup.IStyleConnector.Connect(Int32 connectionId, Object target) in <XamlFilePath>:line 291
  InnerException: 

Edit 2:

The method handler is:

    private void Column_GotFocus(object sender, RoutedEventArgs e)
    {
        ContentPresenter columnContentPresenter =(DependencyObject)sender).FindParent<ContentPresenter>();

        Column column = (Column)columnContentPresenter.Content;

        string message = string.Format("{0} ({1})", column.Name, column.Field);

        ModuleDescriptor.UpdateStatusBar(message);
    }

Answer 1

This is a framework bug and it is already fixed, please download the hot fix to overcome the issue!!

http://support.microsoft.com/kb/2464222

Bug report is here:

http://social.msdn.microsoft.com/Forums/en/wpf/thread/629bfcc5-2005-4947-a001-993524798b52

Download the file here