They probably have a Samsung Smart TV, great TV crap software, full of bugs, poorly designed and a weak impersonation of the Android genuine article! The CM0013 file is I believe a Samsung stupidity because I have many Samsung Smart TVs and somewhat infuriating this file keeps appearing, it can be safely removed, but it will come back every time.
Samsung offer a feature to allow movies to be shared across TVs and PCs using your WiFi/Network, however, the feature once again is poorly designed and as with a lot of Samsung software, has flash user interface but implementation is farcically amateurish. It writes to the source drive and creates additional files and references and I suspect this may be related to your problem especially if the drive directory became corrupted because they were not aware it was being written to and unplugged it (Samsungs program to create this library takes about 30 hours to run on a 2TB drive full of 700k films, so its no wonder people give up because it has all the symptoms of a hang!)
On your PC, right click the drive-->Properties-->Tools-->Check the drive for errors-->Check now. On a 2TB drive, it may take many hours, be patient. It works quicker if you do it from a decent laptop since they usually have better USB3 support.