Hang in unknown location in a very complex WPF application when windows layout changed because of creating ReportViewr in another thread

I have a WPF application with a very complex XAMLs, I need a way to know the point that my application hang on, when I try to pause the execution, the application seems to not be hanging, the pointer will be on this line:

System.Windows.Application myApp;
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myApp.Run(); // <== this line

This is happening when I change the layout of the task bar or when windows explorer crashed (the task bar is hidden), if I do those changes in a heavy repetition, the application will never recover, but when a small change done, the application will recover after minutes, I need to know the cause of this issue, I doubt in the complex XAMLs of my application, but I need a way to know the page or the component, or the whatever the source of this hang.