W3 validation of javascript

Question

I have the following code:

<script type="text/javascript">
var script = document.createElement("script");script.type="text/javascript";var src = "https://www.server.net/live/server.php?request=track&output=jcrpt&nse="+Math.random();setTimeout("script.src=src;document.getElementById('l_tracking').appendChild(script)",1);</script>
<noscript>
<img src="https://www.server.net/live/server.php?request=track&amp;output=nojcrpt" width="0" height="0" style="visibility:hidden;" alt=""/></noscript>

It stops my page from being w3 valid..

Warning Line 578, Column 143: cannot generate system identifier for general entity "output"

Error Line 578, Column 143: general entity "output" not defined and no default entity

Error Line 578, Column 149: reference to entity "output" for which no system identifier could be generated

I know it has something to to with the & in the functions but I don't know how to fix it. Replacing & with & won't work. To whom it may help, thank you!