Wen calling the .abort() method on the XMLHttpRequest that is returned by the $.ajax( ) method you will get a javascript error in IE7. I have written a fix for the problematic area and I have included it below:

Original Code:

// Override the abort handler, if we can (IE doesn't allow it, but that's OK)
// Opera doesn't fire onreadystatechange at all on abort
try {
	var oldAbort = xhr.abort;
	xhr.abort = function() {
		if ( xhr ) {
			oldAbort.call( xhr );
		}

		onreadystatechange( "abort" );
	};
} catch(e) { }

Fixed Code:

// Override the abort handler, if we can (IE doesn't allow it, but that's OK)
// Opera doesn't fire onreadystatechange at all on abort
try {
	var oldAbort = xhr.abort;
	xhr.abort = function() {
		if ( xhr && typeof oldAbort == 'function' ) {
			oldAbort.call( xhr );
		}

		onreadystatechange( "abort" );
	};
} catch(e) { }