If you've got no hardware warranty, swapping the failing internal usb drive will probably fix this. I've successfully revived several dead ZD1100s this way - you pop open your ZD, carefully wiggle out the usb drive (it has no case, and it's hot-glued in), then use something like ImageUSB on your Windows PC to backup the existing drive and restore onto a new replacement (which must be 2gb or more - I use 4gb since I can't find anything smaller), insert the new drive into the ZD and you're back up and running.