Javascript file doesn't exist
The script wants to include a javascript file which doesn't exist on the specified location.
This causes no problem for the performance of this script, because the browser get immediatlely from server the notification that the requested file doesn't exist.
<script type="text/javascript" src="xxx" /> don't work with Internet Explorer
This don't work in Internet Explorer 7 and don't result in an error or warning but in an empty page.