I'm trying to figure out why a container isn't displaying at 100% of the available width.  An example of this is at:  http://dnn.archchicago.org/missions (the Contact Us module below the menu).

The navigation menu is wider than its normal size due to the length of one of the items in the menu.

However, the module below the menu is NOT 100% of the available width.  In the ASCX for the container, the table(s) are set to width=100%.  Nothing else has width specified.  In the CSS, the only time that width is specified, it's also set at 100%.

Can anyone shed some light as to how I can make sure the container fills the available width?

As the poster above said, if your panes are set to a certain width, they will constrain the containers to that width. I also noticed some height definitions in there, you may have more consistant results if you put the height tag on your TR elements, as that will stretch the entire row to X height, however depending on the construction of your tables and nesting, that may not be optimal.

I just discovered that it renders differently in IE and Firefox.

In IE6/7, if the Nav menu ends up being wider than 200 px, other containers in the pane will be narrower.  In Firefox, the containers WILL expand to fit 100% of the width.

As it turns out, the portal Administrator seems to have noticed this particular issue and changed the Page Name text for the problem issue.