Although I had no problem (approx.) 2 wks ago, Dolphin won't mount my Sansa Zip-Clip mp3 player now.

The error from Dolphin is "Error - KIO Client - The process for the mtp protocol died unexpectedly." I tried mounting a thumb drive. It may be unrelated, but for about 2 months the mount initially fails too, with the message
An error occurred while accessing 'Home', the system responded: The device is already mounted: Device /dev/sdb1 is already mounted at `/run/media/***/***'.
But it always works the second time I click on the device name in dolphin. This is not the case with the Zip-Clip.

Is anyone else seeing these symptoms? How to proceed?
Thanks in advance.