Create Forum topic not displaying correctly in Firefox/IE

The Body textarea in "Create Forum Topic" form is not aligned correctly - it floats off to the right, which means that part of it is not visible in FF.

It seems that this is due to an the incorrect alignment of the Forums select box but I am not sure where to fix this.

In IE the "Body:" title is also not aligned correctly, but at least the text area displays below and not next to the Forums select box as it does in FF.