I think I see what you're saying. When cell 1 has lengthy content, it splits up the height of cells 2 and 3 and half causing a gap. If that's correct, would removing cell 3 entirely and putting a table within cell 2 work? It would look like this:
Code:
<table>
<tr><td>1</td>
<td>
content of cell 2
<table><tr><td>table replacing cell 3</td></tr></table>
</td></tr></table>