Here's the original case. All of the cells have images that fill to their given widths except the ones marked "Empty".

|  | Empty
| Empty

If we fill either empty out with text, the problem goes away.

|  | Empty - lots of text here now - and more and more and more text in it
| Empty

|  | Empty
| Empty - this has lots and lots and lots of text in it

Taking away either the cellpadding=0 or cellspacing=0 fixes the problem.

|  | Empty
| Empty

As does removing the explicit width on the table...

|  | Empty
| Empty