I own a Pentax *ist DS. Lately I've been seeing strange behavior related to white balance (WB). For example, with the camera set to the tungsten WB setting, if I take several photos of the same object in succession, I end up with a variety of color casts. One photo will be too warm, the next too cool, the next "just right", etc. These are not subtle variations; they are substantial. I first noticed this problem with the tungsten setting, but I was able to work around the problem by doing a Manual WB adjustment. But now I'm starting to see the problem even with Manual WB. Has anybody else had this problem?? Any idea what's going on, and what I can do about it?