If you go to the Nav screen and press "menu" then touch the screen at the bottom left corner Nav Menu and hold, you will get a new screen that shows a keypad and asks for "diag pin". put in the number 1791 and it will shut off the annoying OK button for the nav. You may need to do this again when it resets itself but it works on my 08 avalanche, i haven't had a chance to try it on the 07 silverado we have but it is the same unit so it should work