There is a setting on the 7D when you can set the behaviors of the shutter button, back focus button, etc... Check that to see what starts the AF drive... I dont have my 7d in front of me so I cant tell you exactly what custom fuction it is, but it's there... with that setting you can set which button starts metering, focus, shutter, etc... IF all else fails, in the custom functions, you should have an option to clear all custom functions... that's a good place to start to default it back to factory settings so you can program it to work the way you want it set up to be.