I was having the same problem. Damn internet explorer is the real problem. I think if you ad the code below to your .css you should be alright. Do a search for "diplay: block" in Google for an explaination of what that code does. You may see some unexpected white spaces in IE after you ad the code. Check out my blog for a solution I found, or do a search for "white spaces in IE" for a couple of more complex solutions.
Code:
}
.clearfix:after {
content: ".";
display: block;
height: 0;
clear: both;
visibility: hidden;
}
.clearfix {display: inline-table;}
/* Hides from IE-mac \*/
* html .clearfix {height: 1%;}
.clearfix {display: block;}
/* End hide from IE-mac */
This code does make your .css w3c non-complient. Hope that helps.