Anyone recognise this? I convert all my bd's to mkv without transcoding. In the latest windows 10, the thumbnail generator has a problem with some of these mkv's and either (a) fails to generate a thumbnail or (b) hangs using 80% of cpu until i cancel it and explorer. In both these cases, the files play fine with videolan and if i run them through the mivtoolnix the resulting mkv shows its thumbnail fine. (I have the impression that it happens when the audio is dd rather than dts) Additionally: On two of these files when I tried to run them through mkvtoolnix the program came up with 'format error 2' or suchlike (note to self: one of these was us poirot season 5 disk 2 episode 1) and I had to re-rip with makemkv to create a file the mivtoolnix would accept.