David Passell passes along this information: "For a long time I have been copying a friend's SD chips to archive-DVDs and also using iDVD, iPhoto, etc. to make playable DVDs. I went through a time though when I thought I was getting corrupted chips. They wouldn't load, I couldn't copy them, and when I tried to play videos (AVI) from them I would get 'end of file errors,' etc. Even with the SAFE/LOCK key in place I would have problems. The underlying problem was that I was plugging the SD > USB adapter into a hub. When I plugged it directly into a Mini USB connector, the problem went away.
Basic principle:
• To avoid corruption, or changes on photo dates, always put the little key on the SD chip to the SAFE/LOCK position.
• Always plug the adapter directly into a USB port on the computer.
• Don't use a hub, not even a powered one.
• Before removing the chip, EJECT the image of the SD, just like a large Hard Drive or USB thumb drive."
From his MacBook Pro at the Sunnyvale, CA public library we hear from John Carter on the subject: "Pam Wickstrom was told by Apple support that you cannot use a USB hub (powered or not) on an Airbook to connect to an external hard drive - the external hard drive has to be connected directly to the Airbook. David’s experience with an SD chip is similar, but I don’t know if he was using an Airbook. So from this we might conclude that you can’t read any external media through a USB hub on an Airbook. This needs to be confirmed."
Upon receiving this info from John here's David Passell's reply, "I'm not sure what an 'airbook' is, I think it means the MacBook Air. However, I am using a Mac Mini. I have three hub-type devices. A Gigaware four-port (powered), a Targus four-port (unpowered) which is in turn conected to a TrendNet KVM switcher which has two USB ports. I have never had a problem with hard drives or USB thumb drives through a hub. I do have my TimeMachine drive connected directly to a Mini USB port. The problem appears to be when I use my Targus USB to SD adapter. SDs apparently do not read properly when plugged in through a hub."