Unable to play few MKV and AVI files when Live Plus is connected to a USB drive

I am using WD TV Live PLUS HD device and using the same with a external HDD connected via USB cable, I am faicing a problem of plaing some MKV & AVI files on my LCD, and the error which i recive is “Unsupported file format”. However, for some other MKV and AVI files were getting played with the same setup.

Also i am not able to update my firmware on the device, although i do not recive any error, but the installation never gets finished and the Device gets restarted multiple times.

mkv / avi are containers. The player may not be able to play the codecs within those containers.

How are you updating your player. What is your firmware at the moment and what are updating it too.