[banshee] Add null check now necessary due to performance fix

[Aaron Bockover <abock src gnome org>]

commit 3421e5599ca65cbc125d7eab5d776a661dc4dc1d
Author: Aaron Bockover <abockover novell com>
Date:   Mon Apr 27 22:47:00 2009 -0400

    Add null check now necessary due to performance fix
    (cherry picked from commit 0f2c85cb6cc9af076437d9512c678a6c68fc4f5b)
---
 .../NotificationAreaService.cs                     |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/src/Extensions/Banshee.NotificationArea/Banshee.NotificationArea/NotificationAreaService.cs b/src/Extensions/Banshee.NotificationArea/Banshee.NotificationArea/NotificationAreaService.cs
index 2019b15..8ec2fbd 100644
--- a/src/Extensions/Banshee.NotificationArea/Banshee.NotificationArea/NotificationAreaService.cs
+++ b/src/Extensions/Banshee.NotificationArea/Banshee.NotificationArea/NotificationAreaService.cs
@@ -388,6 +388,10 @@ namespace Banshee.NotificationArea
         
         private void ToggleRatingMenuSensitive () 
         {
+            if (rating_menu_item == null) {
+                return;
+            }
+            
             if (ServiceManager.PlayerEngine.CurrentTrack is DatabaseTrackInfo) {
                 rating_menu_item.Show ();
             } else {