DIVs messing up tables

When I put DIV tags containing hidden information (for popups) into my table,
it messes up my alignment. I'm not talking about Design View in DW with
invisible elements on . . . I'm talking about the IE preview.When I get the
layer/div close to the trigger button, it bumps my column away from where it
should be. If I put the divs in an external table, it works, but I don't want
to do that. Ideally I would be able to put them in the same cell as the
trigger image. What is causing my problem and how could I place the tag near
an image without messing up TD size?