It was probably one of those damn 17-85mm pieces of rubbish that Canon won't even cover under extended warranty anymore (probably because we've sent so many back to them with Error 01). I've thought of throwing those things a few times. ;)
@kezzam You can try cleaning the contacts (use a pencil eraser), but it is probable that it will need repairs. Hope that it is under warranty - if it is not, I suggest buying something else.
Not mine and I am partial to a high shot or two.
@icywarm Hahaha! That made my day! :D