So, I got a great deal on a near-mint condition Xti. The previous owner took about 500 pics. No issue.
I took about 30 pictures to start to get familiar with the camera. I transferred them to my computer. I went to my shop and started taking pics of my R90 project. Then, the camera screen said something like "Card Error" and when I go to view the pics, it says the card's empty. I turn it off/on, take out the card, put it back in, and it just says the same error.
What's the problem?