Added an extra check for removing a named cache property - calling it when it didn't exist caused an exception.

src/core.js

@@ -509,6 +509,7 @@ jQuery.extend({
 
 		// If we want to remove a specific section of the element's data
 		if ( name ) {
+			if ( jQuery.cache[ id ] ) {
 				// Remove the section of cache data
 				delete jQuery.cache[ id ][ name ];
 
@@ -517,6 +518,7 @@ jQuery.extend({
 				for ( name in jQuery.cache[ id ] ) break;
 				if ( !name )
 					jQuery.removeData( elem );
+			}
 
 		// Otherwise, we want to remove all of the element's data
 		} else {