I'm a relatively new PT user so this is probably a bonehead question... I have Pro Tools 6.4 running on Panther and a dual 2 GHz G5. The send section on the mix window has mysteriously become a lighter gray than the rest of the mixer and only one thing shows up which is a button with a small "d" on it. If I click on this I can use one send. It wasn't that way when I installed it a week ago!! I've looked in the manual etc... anyone know what's up with this?