Trying to remove an extra paragraph tag

When I want to give an image in my post a border I use this code:

<div class="imgborderL"><p><img src="http://www.familywebwatch.com/blog/wp-images/microphone.jpg" alt="Open Invitation: What's on your mind?" /></div>

The imgborderL (to set an image to the left) and another one (imgborderR) for the right, I use this css:

.imgborderR {
	float: right;
	margin: 0px 0px 10px 10px;
	background-color: #ffffff;
	border: 1px solid #999;
	padding: 2px;
	line-height: 0;
}

.imgborderL {
	float: left;
	margin: 0px 10px 10px 0px;
	background-color: #ffffff;
	border: 1px solid #999;
	padding: 2px;
	line-height: 0;
}

.imgborderL p, .imgborderR p {
  margin: 0;
}

The issue is when I validated this my home page I get the following error:

Error Line 252, column 149: end tag for "p" omitted, but OMITTAG NO was specified .

I see the extra “p” tag in there, but I’m not intentionally adding it.

How can this be removed so that my code validates?