I have recently brought Mezzmo after many trials of other DLNA software and was very happy with its performance. All was going great with no noticeable issues on my Panasonic Viera THP58VT20A. I updated to the latest release 220.127.116.11 and now having issues with some MKV and MP4 files(not all) that had previously played. I suspect it is something to do with transcoding as the files work with no problem streaming on a WDTV Live box I have on a different TV, but will leave that to the experts if they can figure it out. I have attached an mp4 error of logging files for support.
hope you can rectify