[Plugin: SyntaxHighlighter Plus] automatic renders and diff. code appears?

Hi, for some reason this plugin renders the code posted automatically. THis is what I post:

<div id="authorbox">
    <?php if (function_exists('get_avatar')) { echo get_avatar( get_the_author_email(), '80' ); }?>
    <div class="authortext">
       <h4>About <?php the_author_posts_link(); ?></h4>
       <p><?php the_author_description(); ?></p>
    </div>
</div>

and this is what appears once I click on publish:

<div id="_mcePaste"><div id="authorbox"></div>
<div id="_mcePaste"><?php if (function_exists('get_avatar')) { echo get_avatar( get_the_author_email(), '80' ); }?></div>
<div id="_mcePaste"><div></div>
<div id="_mcePaste"><h4>About <?php the_author_posts_link(); ?></h4></div>
<div id="_mcePaste"><p><?php the_author_description(); ?></p></div>
<div id="_mcePaste"></div></div>
<div id="_mcePaste"></div></div>
<div id="authorbox">    <?php if (function_exists('get_avatar')) { echo get_avatar( get_the_author_email(), '80' ); }?>    <div>       <h4>About <?php the_author_posts_link(); ?></h4>       <p><?php the_author_description(); ?></p>    </div></div>