this is an issue with IE and forms that contain only one element. When the form contains only one element, the submit button is not passed by IE when the form submits. The workaround for this is to change DataAssist search to use the text box for the trigger instead of the submit button.
On the results page, find the following line of code:
if ((isset($_POST["WADbSearch1"])) && ($_POST["WADbSearch1"] != "")) {
and change it to:
if ((isset($_POST["searchFormEnhanced"])) && ($_POST["searchFormEnhanced"] != "")) {