Pages going haywire in edit view

Ive been trying to edit pages on my site, this page for instance: https://www.rerdownloads.com/?page_id=2249
and each time I go into edit view, halfway down the page, its like the table disappears and the pictures and texts are all jumbled up all over the place.
What I think this might be:
In DreamWeaver I added some text outside the table where it says td>tr>tbody> etc, but that was fine before.
Or…I had added a javascript allowance thing to header.php but on the 2 pages where I have used this Javascript, it is fine.
Does anyone know what this might be? It did it earlier then was fine, now it is doing it again. The pages look fine until I go into edit view. When I view the HTML its like some of the code is missing. The code that makes the table i think.

If anyone could shed some light or know what I am talking about, would be greatly appreciated.

thanks
Henry