Help! The last two days of using my camera I've had some issues. I always shoot in Manual (M) on my Canon Rebel Xti. Over the last few days, with my cam in M mode, it hasn't been letting me adjust my aperture or speed. It's even bumping my ISO. What in the world is going on?! I have to kick it out of M mode and turn it back so I am able to make adjustments. It's reading my Manual mode as P mode. Could this be something silly I am doing or should I bring it in to get looked at?? Thanks..