diff --git a/wp-includes/js/thickbox/thickbox.css b/wp-includes/js/thickbox/thickbox.css
index 6c2b211991..eac043423e 100644
--- a/wp-includes/js/thickbox/thickbox.css
+++ b/wp-includes/js/thickbox/thickbox.css
@@ -33,6 +33,7 @@
 .TB_overlayMacFFBGHack {background: url(macFFBgHack.png) repeat;}
 .TB_overlayBG {
 	background-color:#000;
+	-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=75)";
 	filter:alpha(opacity=75);
 	-moz-opacity: 0.75;
 	opacity: 0.75;
diff --git a/wp-includes/js/thickbox/thickbox.js b/wp-includes/js/thickbox/thickbox.js
index 0b079e3fc0..df602f3cff 100644
--- a/wp-includes/js/thickbox/thickbox.js
+++ b/wp-includes/js/thickbox/thickbox.js
@@ -281,8 +281,9 @@ function tb_remove() {
 }
 
 function tb_position() {
+var isIE6 = typeof document.body.style.maxHeight === "undefined";
 jQuery("#TB_window").css({marginLeft: '-' + parseInt((TB_WIDTH / 2),10) + 'px', width: TB_WIDTH + 'px'});
-	if ( !(jQuery.browser.msie && jQuery.browser.version < 7)) { // take away IE6
+	if ( ! isIE6 ) { // take away IE6
 		jQuery("#TB_window").css({marginTop: '-' + parseInt((TB_HEIGHT / 2),10) + 'px'});
 	}
 }
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index f639fb6f1f..ebe4365039 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -153,7 +153,7 @@ function wp_default_scripts( &$scripts ) {
 	$scripts->add( 'jquery-table-hotkeys', "/wp-includes/js/jquery/jquery.table-hotkeys$suffix.js", array('jquery', 'jquery-hotkeys'), '20090102' );
 	$scripts->add_data( 'jquery-table-hotkeys', 'group', 1 );
 
-	$scripts->add( 'thickbox', "/wp-includes/js/thickbox/thickbox.js", array('jquery'), '3.1-20080430m');
+	$scripts->add( 'thickbox', "/wp-includes/js/thickbox/thickbox.js", array('jquery'), '3.1-20090123');
 	$scripts->add_data( 'thickbox', 'group', 1 );