DVD in external drive "disappeared"
I am actually asking this question for a friend of mine who owns an external hard drive and is trying to use a DVD that my friend inserted into the drive. The DVD appeared on the computer for a second, then disappeared. Not even Disk Utility acknowledges the DVD's presence in the drive.
The currently-running operating system is Mac OS X 10.9.5, and the iMac and external DVD drive are just a few years old. There is no internal drive on the iMac.