Blinking/flashing images in firefox

[mr_c0w]

My images are blinking when I mouse-over in Firefox. They work fine on chrome and safari. I think I've narrowed it down to the tag that wraps the images, but I don't know why it would cause that problem. (The left image does not have an tag around them and it is fine, but the right image does, and it's blinking.) Full HTML: http://mf.atlantadesigngroup.com/firefox.phpRelevent HTML:\[code\]<div id="portfolio"> <div class="portfolio"> <img src="http://stackoverflow.com/questions/15571825/images/portfolio/bw/uploaded1.jpg" class="portfolioImg"></div> <div class="portfolio"> <a href="http://stackoverflow.com/questions/15571825/firefox.php"> <img src="http://stackoverflow.com/questions/15571825/images/portfolio/bw/uploaded4.jpg" class="portfolioImg"> </a> </div></div>\[/code\]Full CSS: http://mf.atlantadesigngroup.com/css/mignonFowler.cssRelevent CSS:\[code\]/*portfolio page*/#portfolio{ display: table; table-layout: fixed; width: 980px; padding: 10px;}.portfolio{ display: table-cell; height:440px; border: #000000 solid 10px; overflow: hidden; position: relative;}.portfolioImg{ height: 100%;}.portfolio div{ height: 100px; width: 100%; position: relative; top: 100px; background-image: url('../images/captionBg.png'); background-position: bottom; background-repeat: repeat-x;}.portfolio div p{ display: block; width: 100%; padding-top: 70px; color: #c9b52e; text-align: center;}\[/code\]