Your image map code works just fine for me if I use a fully-qualified URL for the map area HREF property.
<img src="sampleimage.png" alt="screen1" width="3836" height="768" usemap="#Map" border="0" />
<map name="Map" id="Map">
<area shape="rect" coords="1090,176,1636,664" href="http://www.google.com" alt="imagespot1" />
</map>