That's what it is then. You'll need to go back to the original computer, right click the disk in the tree, and there should be an option to close the disk or make it readable in other computers. If not, try typing directcd into the 'run' command box in the start menu. A window should open, and somewhere in there is an 'options' button with an option for closing the disks on ejection. It's not a one-size-fits all solution because disk writing is done by so many programs now... If the orig computer is inconvenient to get to, the Kinkos has a good shot of working, especially if you can't normally write to CDs with the drive on your system.