Table cells collapse unless there is something to hold them to a certain
width. Even telling them to be a certain width, such as 400 pixels, is not
enough since the browsers don't have to follow that specifically, then can
shrink things as needed. An old web-developer trick is to create a gif image
that is 1 pixel high by 1 pixel wide. You then place this image somewhere in
the table cell (often towards the bottom so it doesn't interfere with the
text) and set it's width to be whatever you need the table cell to be, such
as 400 pixels.
Hope this helps,
Mark Fitzpatrick
Microsoft MVP - FrontPage