Here's' a correspondence I got from a friend on Facebook. She's got a Canon, but I am thinking the problem/solution could possibly not be camera specific

1. Hey guys...
Went to the zoo today and took some pics... got home to download them and they are all white!!!! What caused this? any ideas?

2. Oh and of course they were fine when I took them and I have taken some just now and they are ok

3. I just had it on the auto setting. I tried reloading the card, after I downloaded them, nothing changed. They were just fine when I reviewed them when I was at the Zoo....but sometime coming home that happened. The camera was in the car with me. ???? I'm so sad that I lost them! Nothing great but just a couple pics from a temporary dinosaur exhibit :(
I just wanna make sure my card is not bad... but why would they show up good and 3 hours later go bad?

I'm thinkin' all the pictures she took were of the polar bears, but,,,,,,

Any ideas?

john