Sorry if this is old news. I've tried this on a pair of Macs, one 10.6.2 and the other 10.5.8, both with iTunes 9.0.2. The gist of the issue is that if you have your Droid mounted, and then launch iTunes, iTunes will wreak havoc w/ the USB bus and ultimately you'll get some I/O errors reading and writing to the Droid's SD card. To test I did the following: Without iTunes running, plugged the Droid into the USB bus and mounted the SD card Wrote some files to the SD; this worked fine. Also read files from the SD fine. With the Droid still mounted, launched iTunes to look for tunes to copy (I still use iTunes for music library management :icon_eek Attempt to copy files to SD card failed (see the first attachment below which is on Leopard 10.5.8) For giggles, attempted to create some new directories on the SD card via the command line. See the second attachment. The only fix for this is to unplug the Droid from USB and re-plug it. You won't be able to unmount the device (by dragging it to the trash), nor will a force unmount (in Snow Leopard) suffice. So in short, do one of the following: Don't use iTunes If you need to use iTunes, make sure it is running *before* you mount the Droid. If you mount after iTunes is running, all seems OK. Curious if this is a similar issue on Windows. Also if other Mac users could confirm this Mac behavior that'd be cool too. :icon_ banana: Still <3 the freedom of my Droid more than the restrictions of my iPhone.