winword process not closing after task complete via csharp (c#)

Following is the lucky code that works fine

Word.Document docObject
Word.ApplicationClass word_app = new Word.ApplicationClass()

docObject.Close(ref vk_false, ref vk_missing, ref vk_missing);
word_app.NormalTemplate.Saved = true;
word_app.Quit(ref vk_missing, ref vk_missing, ref vk_missing);
word_app = null;
GC.Collect();


javascript:void(0)
Help from Microsoft
http://support.microsoft.com/kb/285885