This sounds like it might be a defective CCD imager. If so, Canon should fix this for you for free, including free shipping both ways. This is regardless of your camera's warranty status. Please check the following two links for more info:
I see OK picture on LCD display before taking a photo, so I take one. When reviewing photo that was...
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I see OK picture on LCD display before taking a photo, so I take one. When reviewing photo that was taken, I can see on LCD display photo with patterns that are repeated from top to bottom and colors that are somewhere between sepia and color technique.
the rechargeable nimh batteries only last 20 sec even though fully charged, could there be a problem...
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the rechargeable nimh batteries only last 20 sec even though fully charged, could there be a problem with the battery that does the time/date memory