Hi, I didn't re-format it. it's been working fine and I just took photos on it, got home, put it in to a friend's computer which came up with an unrecognized error message so I removed the card and put it in to my own computer when I returned home to find that most of the files that were on there were wiped and there were only about 20 left, so the other photos disappeared, and now I only have 50mb space on there! Confused!