Firefox Tables Glitch?

An interesting thing is happening with a layout I am coding. I used tables to code the following, except in Firefox, wierd 2px gaps appear between some of the tables / table rows. I don’t know whats causing them at all. They don’t show up in IE6 at all! I also found it interesting that my OTHER layouts work just fine, even though I think I used the same method to code them. Also if you notice at the bottom of the Firefox image, the bottom doesn’t have a gap… why is this so? It is in fact a separate image, yet it doesn’t gap!

Take a look (sorry for the size, i was too much in a hurry to compress :P):

See, no gap at the bottom one… wierd…

And somehow IE got it right:

Remember its really wierd that it only happens with this layout; the same method I used to slice and code other layouts still works in Firefox, no gaps at all. I’m thinking that it might be something to do with Firefox 2? Not sure.