Quote Originally Posted by Sinh Nhut Nguyen


When this problem happened first thought was of mykeyboard and my PS controller, I beat the heck out of those two too, but they're easy to clean and fairly cheap to replace. BTW I don't think the rubber "blister" broke because the feel of the button is still normal and is exactly like the one on the vertical grip.
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Bingo! I'd suspect problems with your vertical grip. This happens on my girlfriend's 40D with increasing frequency lately. Sometimes removing/replacing the grip solves the problem, but once or twice I've had to put the camera together grip-less to get it to function. Makes me wish Canon made their battery doors and grips like my old Minolta (the grip had space for the camera's battery door still attached in its native position; no door removal necessary).