Firstly, you’re in the wrong forum … this forum is WDTV Media Player (Personal Edition) released 2014
not the WDTV Live Streaming … released 2011 (i will notify a mod to move this post)
Secondly, if you read the forums you’ll notice for the last several weeks people having issues mainly with MP4 files on the Latest Firmware 2.02.32
So, if you updated to that version recently … then that’s the likely cause.
Advice ? Rollback to Firmware Version 2.01.86 and wait until WD release the next Firmware Update that will hopefully address the issues.
Follow the steps in my Rollback Guide.