Problem with table alignment in posts for TwentyTen theme

I’m trying to add a three column wide, ten row tall table to each of my posts. The code itself is fine, I’ve tested it on other themes, but when inserting into a TwentyTen post, I run into alignment problems.

The main problem is that when I insert an image as the first object in the first column, it bumps all the content in the second and third columns down underneath it so that there’s a huge gap in the second and third columns with no text until after the image. If I add text right before the image, then this problem doesn’t happen… What could be causing this??