Escaping HTML tags in teaser

I noticed that some of my teasers were not closing HTML tags. This would result in the HTML markup cascading down the page- i.e. every node below would appear in bold as the bold tag was not closed (the teaser break came before the tag was closed)

I tried to edit these teasers to put in the close tags. However, the teaser was then processed so that all markup was converted to escape characters, so that the HTML markup itself appears in the teaser view. Note that the input type is set to "Full HTML."

For example, what should appear as:

Roboticist Hod Lipson wants you to stop shopping and use his portable 3-D printer to make your own stuff

(note that the image tags don't show up here because the drupal.org's filtered html does not allow it, but you get the idea)

appears in the teaser view as:

<img class="left" alt="desktop%20factory.jpg" src="http://www.treehugger.com/desktop%20factory.jpg" width="250" height="314" />

<p>Roboticist Hod Lipson wants you to stop shopping and use his portable 3-D printer to make your own stuff</p>

because the html in the teaser view is converted to the escape characters:

&lt;img class=&quot;left&quot; alt=&quot;desktop%20factory.jpg&quot; src=&quot;http://www.treehugger.com/desktop%20factory.jpg&quot; width=&quot;250&quot; height=&quot;314&quot; /&gt;

&lt;p&gt;Roboticist Hod Lipson wants you to stop shopping and use his portable 3-D printer to make your own stuff&lt;/p&gt;

(Let me know if you are having trouble understanding my explanation)