The music note with a line through it means that it is in silent mode. If you want other ways to make it silent if you doubt the holding down of #, press the power button once, and you are given choices on what profile you want to use. You can also press the menu button and look for "Profiles". The default place for that would be Menu - Tools - Profiles.
Or if it still makes sound even in silent mode, I am SURE somebody messed up with the silent profile. Edit it to set your preference.
