The system is hanging when loading a specific incident. Internet Explorer may show a message saying that the page is not responding and that it needs to recover webpage, or you are not able to click on any field in the form. The same incident is correctly loaded with Firefox.
If this behavior occurs due to images like screenshots in a HTML field on the form, for example after receiving an email with images shown in the HTML enabled Description field, then, the solution is to increase the size of the HTML Editor control field, both in width and in height. This will render the images correctly to improve performance.