Invalid Location of tag (DIV) Error __div

The HTML tags in the JSP file are as follows, prompted in the Eclipse environment: Invalid Location of Tag (DIV).

<a id= "test1" class= "Mitem" href= "#" >
</img>
<div id= "a-in-1" class= "a-in" ><div class= "a-in-m" ></div><div class= "A-in-r" ></div> </div>
</a>

phenomenon: Enter the page under the firefox3.6, or enter the page sometimes the interface shows chaos. But under the ie,firefox3.0 all show normal.

Workaround: replace the <div></div> label under the <a></a> label with <span></span>, as follows:

<a id= "test1" class= "Mitem" href= "#" >
</img>
<span id= "a-in-1" class= "a-in" ><span class= "a-in-m" ></span><span class= "A-in-r" ></span ></span>
</a>

The reason should be that the combination of <a></a> and <div></div> labels causes browser parsing errors