When the Test List for this WPF application is being executed, one of the tests stops running (without obvious reason). This happens very randomly.
Expected behavior: The test fails and the next test from the test list is executed;
Actual behavior: Nothing happens. The Test Runner do not do anything unless we close the WPF application. After that the next test from the test list is executed. 

To reproduce: Access to the application and steps to reproduce are in the internal description.