FWIW I had the same issue with my Sony XBR-800 having fairly consistent freezes, I was positive it was the Sony as it usually seemed to be physical discs playing when this happened, especially 4K discs. The Sony support team I spoke with a number of times had suggested things I was pretty sure it wasn't, HDMI cable, try a different HDMI input on the AVR, etc. I eventually got around to ruling all those things out, would still get a freeze even with a Premium certified HDMI cable from the player to the AVR and from the AVR to the TV. I had tried different inputs on the AVR too. I also run a cable to the wall to a keystone jack (HDMI coupler, female to female) and in wall is a cable going to the TV so that I can have mostly invisible cabling and that cable was replaced when I had the TV off the wall. It wasn't occurring with my 4K Fibe TV box therefore it can't be the AVR or the TV or any cables and must be the player right?
WRONG! On a whim I ordered a brand new HDMI coupler keystone jack from an Amazon seller that had the HDMI logo on it just for peace of mind that I'd TRULY tried every part of the chain, once I replaced the keystone jack a couple months ago the problem went 99.99% away. Sweet!!
I really like the Sony's GUI and love being able to stream surround FLAC over my network via PLEX on my PC as I have backed up the vast majority of my Blu-ray and DVD-A collection there, so easy. Glad I was able to suss out my freezing issue. A keystone jack, mother puss bucket!!