Discussion on the IRC channel confirms this bug is happening for other people. It also confirms that this bug is not present in Internet Explorer 8 running in Internet Explorer 7 developer mode, only in the real Internet Explorer 7.

The first JavaScript error is in jQuery, line 20, character 1335, "Error: Number expected." The second is in the JavaScript above, line 15, character 9: "Object doesn't support this property or method."

The problem is in the sortOrder function defined starting at line 2116:

sortOrder = function( a, b ) {

alert(a.sourceIndex - b.sourceIndex);

var ret = a.sourceIndex - b.sourceIndex;

if ( ret === 0 ) {

hasDuplicate = true;

}

return ret;

};

When a and b are elements from an XML DOM, they do not have sortOrder attributes. This function subtracts undefined from undefined, gets NaN, stores it in ret, and returns it. But the sort() function is expecting a number to be returned, hence the error.

Sorry, I should have said line 2108 in my previous comment.

If I comment out this entire sortOrder function and the if statement that creates it (2108-2116), the code falls back to the third sortOrder function, which uses createRange() and compareBoundaryPoints() to figure out the sort order. This sortOrder function appears to work properly.

In other words, this patch appears to fix the bug:

--- jquery.1.3.js.bak	2009-08-12 19:12:56.000000000 -0700
+++ jquery.1.3.js	2009-08-12 19:38:27.000000000 -0700
@@ -2104,14 +2104,6 @@
 		}
 		return ret;
 	};
-} else if ( "sourceIndex" in document.documentElement ) {
-	sortOrder = function( a, b ) {
-		var ret = a.sourceIndex - b.sourceIndex;
-		if ( ret === 0 ) {
-			hasDuplicate = true;
-		}
-		return ret;
-	};
 } else if ( document.createRange ) {
 	sortOrder = function( a, b ) {
 		var aRange = a.ownerDocument.createRange(), bRange = b.ownerDocument.createRange();

However, I do not know enough about jQuery to know whether removing this code has other adverse effects.

This was fixed in jQuery 1.4.