I've been blogging for a week, and recently noticed a problem when trying to view my site with IE 6 and IE7.
After hours of changing themes and still not finding the solution, I finally came upon this post:
Which led me to the solution.
Basically, if you write up your posts in MS Word, when ready to paste into WordPress, do not just right click --> paste. Use the "paste from Word" button in wordpress. This removes all formatting that MS Word installs around text and should prevent the display error. Or, dont write up your posts in Word, use NotePad.
This is probably basic blogger knowledge, but I never learned it!