Unfortunately there's no real way to figure it out without getting down and dirty with the theme code- Microsoft's annoying in that they feel that "standards aren't for us so we can basically make our browser display things however we want it to and pretty much screw developers and make them hate us."
However, if you can figure out something to do with CSS to fix the problem in that browser, it's not too hard to work out. The easiest thing I can think of is to do something like this in your header.php file:
<?php if(is_single()) { ?>
<!--[if IE 7]>
Magic CSS that fixes the problem, applied only if this is a single post page and if it's IE 7
<![endif]-->
<?php } ?>
That's the set of "comparison operators" (yay jargon) you need to apply any styles necessary to fix it.
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