Using of USER FORMS Test complete get crash?

From your code, it looks like UserForm1_OnShow is an event handler assigned to the form's Show event. Calling Show() inside this event handler creates an infinite recursion, which causes the crash.

There're two ways to show a form.

1) Modal mode - the script is paused until the user closed the form.

function sa()
{
  var res = UserForms.UserForm1.ShowModal();

  if (res == mrOK) {
     Log.Message("Form was closed via OK button.");
  }
  else {
     Log.Message("Form was closed via another button.");
  }
}

For this to work, make sure to set the ModalResult property of the form buttons in the form designer. Example for the OK button:

2) Non-modal mode - the script execution continues after the form is displayed, and the script should explicitly close the form when it's no longer needed.

function sa()
{
   UserForms.UserForm1.Show();

   // Do something
   // ...

   UserForms.UserForm1.Hide();
}

Hope this helps!