While working on another issue I discovered this one.  Please use the attached project and you should easily duplicate.

I'm currently using 2010 R1.  Basically the issue is that the grid within a table affects the size of the table even though the grid's table cell has been set to a specific size.

Load the project and then run it.  I turned on the table borders so you can see clearly.  You can use the Best Fit on the columns and you'll see as they expand, they "push" the cell size which in turn push the table column next to them (I put a combo box for reference) to the right.

You can also see this by adding more columns.  Just select several or all the columns on the grid that are not initially visible and you'll see what happens.

I need to be able to have multiple grids in a layout where the grid's UI changes do not impact anything outside of itself as it seems to do now.  The grids are all paired with WebMenuBars because that's how we use them in our environment.

[EDIT] reattached zip file and tested it.