Well, IE has a bug that causes it to go into "Quirks Mode" if this is the case...and that messes up the page rendering.
You can fix this by making a simple hack to the index2.php and offline.php files:
find this in the files ( ~line 123 in index2.php; ~line 63 in offline.php)
// xml prolog
echo '';
and change it to this:
// xml prolog
// echo '';
And don't foget to keep track of this hack, as it will be overwritten by the next Joomla! update you apply
