Warning about hot-swapping USB CD-RW drives while powered-on:
"USB devices may be hot-swappable, but some caution is still needed. Dave Heyman is an Authorized Apple Service Provider. He reports that he has had to replace the ATA-to-USB logic boards in several Sony and LaCie USB CD-RW drives. As to the cause, he writes: "In at least three cases, the problem occurred after the drive was unplugged while it was still powered up. We are telling our customers to power down the computer and the drive before disconnecting. You could probably get away with just powering down the USB drive, but I am not going to experiment to find out."
from MacFixit, today 05/19/00