I recently got a DD, as well as Mario Artist: Paint Studio and Sim City. Until now, both disks worked. However, Mario has suddenly stopped reading, I get error 23 every time. Sim City still works. There looks to be a handful of very tiny marks on the disk, like fluff, and a faint ring that follows some of the disk's circumference. On the advice of the seller I gently cleaned the disk with a cotton bud and isopropyl, but still no luck, so they recommended I reach out here. Any help would be mega appreciated!