I have the same issue with both of my memory cards.
When I insert the card and download my images, they all appear as they should. However, one by one the photo's will being to scramble. Some will be half toned in another colour, others will have three uneven portions that do not match up.
I have tried using several different programs to see if this will make a difference, however it seems that as time goes on, more and more of my images are being ruined.
It's absolutely heartbreaking to see them self destruct like this, and I was wondering if anyone else has had a similar problem or has an idea on how to fix this?