Strange ! Can you play with sound any other videos avi's or mkv's that happened to be already on your pc also maybe worth rebooting your pc. Looks like I was lucky no problems whatsoever -except can't play HD
Yes, I can even play the .ts files if I copy them across to the PC. Also I have tried a different PC and got the exact same problem.
I'm not sure why you cant play HD though. Apart from no sound, they play fine for me.