The validator incorrectly accepts a self close for the script tag as valid html syntax.  However, the html specs require a </script> follow a <script ... > tag

ie.  <script ... />  is treated the same way as <script ... ></script>

All of the browsers will gobble up the entire rest of html page looking for the </script> close tag, and therefore display nothing.

I was cleaning up a web page changing all of the <br> tags to <br />, etc, and I absentmindedly collapsed a <script ... ></script> pair down to <script ... />.
The validator accepted the self close syntax, but the page no longer renders.