Only attempt to use the IE technique for setting opacity if the filter property exist...

diff --git a/src/css.js b/src/css.js
index ad0da64..cb65c0b 100644 (file)
--- a/src/css.js
+++ b/src/css.js
@@ -49,7 +49,7 @@ jQuery.extend({
                var style = elem.style || elem, set = value !== undefined;
 
                // IE uses filters for opacity
-               if ( !jQuery.support.opacity && name === "opacity" ) {
+               if ( !jQuery.support.opacity && name === "opacity" && style.filter ) {
                        if ( set ) {
                                // IE has trouble with opacity if it does not have layout
                                // Force it by setting the zoom level