[SOLVED] First post and individual post pages display incorrectly in IE

Atahualpa 3.2
WP: 3.0.1

This is an error that is only happening in Internet Explorer (I'm viewing it on an XP machine if that matters), and it's driving me bonkers. Luckily this is just a test site for a redesign of newdust.com, so none of this is live.

If you'll take a look at the test site (longlivetherobot.net), you'll notice first of all that I have made quite a few customizations to the stylesheet, header.php, and index.php. If this were a car I've definitely voided the warranty at this point, but hopefully that won't be a problem. As a reference, view the site in Firefox to see how it should be displayed. In IE, you'll notice that for some reason the first post on the homepage (as well as individual post pages) doesn't seem to follow the styles I've defined for it, however as you scroll down you'll notice that every post after it is displayed as it should be. Also widgets have a 1 pixel .png transparent background that's set at "repeat scroll", and it seems to not display properly on IE either. I have installed an IE PNG fix plugin hoping that would fix the issue, but it did not.

Unfortunately I can't list off all of the tweaks and modifications I've made to the code off the top of my head, but if you have an idea of what might be causing this I will do my best to pinpoint any change I made. Thanks in advance for helping!