When I click on any of the archives links or categories links in Firefox 4, everything goes well, as seen in this pic: http://www.1stroundbust.com/1br-ff-correct.jpg
When I do the same thing in Internet Explorer 7, the social buttons seem to want to float left and below the logo. Also, posts seem to want to stack up on top of each other, as seen here: http://www.1stroundbust.com/1br-ie-incorrect.jpg
This problem seems to happen at random. But when I refresh the page in IE7, the problem seems to go away, and everything lines up the way it should.
Not sure where to start looking for this problem, whether it's an IE problem, a CSS problem, whether I wrote bad code, etc.
I'm using WordPress 3.1.3, and I created my own theme from scratch, more or less. My website is http://www.1stroundbust.com. Any feedback is greatly appreciated.