A couple thoughts:

1. Drivers may render pages differently depending on screen size. If IE is broken using the same window size, try maximizing the browser window.
2. You didn't say whether you actually checked the page source in your IE test to confirm that the element it claims to not be able to find is actually there.
3. In AJAX-heavy pages, I've seen different drivers handle sub-elements very differently, especially if they're "hidden" in some way. I have gone so far as to build action chains that hover over or click on each and every godforsaken child element all the way down to what I'm looking for, just to make sure that what I'm trying to get at is exposed.

A couple thoughts:

1. Drivers may render pages differently depending on window size. If IE is broken using the same window size, try maximizing the browser window.
2. You didn't say whether you actually checked the page source in your IE test to confirm that the element it claims to not be able to find is actually there.
3. In AJAX-heavy pages, I've seen different drivers handle sub-elements very differently, especially if they're "hidden" in some way. I have gone so far as to build action chains that hover over or click on each and every godforsaken child element all the way down to what I'm looking for, just to make sure that what I'm trying to get at is exposed.