I've had a couple things happen. First time the card lost the FAT table and neither my computer nor the Q could see it. Second time (after a full Fat32 format) I suddenly had a card of about 100 empty folders named " . ". Other things that have happened is I've ended-up with garbage named files, everything gone except for one folder and a couple gibrish folders, etc. I have a 2GB card on the way. When that arrives I'll probably return the 4GB or see about getting another one. It is either all or nothing. When it works, it works 100%. When it "breaks", it's fully unusable and I have to do a reformat on my PC.