I'm having the same issue. All the search results I get are not correct. Started hitting me when I dragged/dropped a control from the toolbox onto my wpf form.
I deleted all the visualization toolbox items, then I shut down VS, moved the visualization dlls, and restarted VS. Fixed the issue.
This also worked for me because I was getting the same error ...
"Error 1 '/Microsoft.Windows.Design.Developer;component/themes/GridAdorners.xaml' value cannot be assigned to property 'Source' of object 'System.Windows.ResourceDictionary'. Cannot create instance of 'GenericTheme'
defined in assembly 'Microsoft.Windows.Design.Interaction, Version=18.104.22.168, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Exception has been thrown by the target of an invocation. Error at object 'ResourceDictionary_4'. D:\Visual
Studio 2008\Projects\WOWTrax\WowTraxDesktop\Window1.xaml 6 5 WowTraxDesktop"
I right clicked and deleted the all the Data Visualization toolbox items, then shutdown visual studio. The edited my *.csproj project file and removed all data visualization references ...
<Reference Include="System.Windows.Controls.DataVisualization.Toolkit, Version=3.5.40128.1, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />
... except for the wpftoolkit reference that I kept ...
<Reference Include="WPFToolkit, Version=3.5.40128.1, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
I then opened my solution and re-added the reference to System.Windows.Controls.DataVisualization.Toolkit
This worked for me.