Why is my form being submitted differently when I use the mouse instead of the keyboard

I have a coldfusion page with a form on it. If I click on a field, use the backspace key to delete the current value, and then enter a new value the form works correctly. If I use the mouse to highlight the data in a field then when I release the mouse the code does not work correctly, it goes to the file defined in the action. When it work correctly the action file is called without refreshing the screen. I have not been able to create a sample page that demonstrates this. A simple example of my form is:

      <form method="post" id="frmUpdateIssue" name="frmUpdateIssue" action="d7a.cfm">
            <input type="hidden" name="iIssueID" value="23">
            <input type="text" name="testVar" onfocusout="ClickEvent()" value="7" />
      </form>
      
      <script type="text/javascript">
            function ClickEvent ()
            {
                  jQuery("#frmUpdateIssue").submit();
            }
      </script>

I understand that when I release the mouse button that the ClickEvent function should be called. What I don't understand is that when I highlight the value using the mouse and then release the mouse that the line:

jQuery("#frmUpdateIssue").submit();

behaves differently (page is redirected to d7a.cfm) than when I use the backspace key to delete the value and then type in a new value. In this case the ClickEvent function is called and the form is submitted without a redirect to a new page or screen refresh