VU+ Duo playiback problems on DUO

[johnny bravo]

ok - ive got a genuine vu+duo and a genuine vu+uno bothe have same blackhole images 2.0.6 on them, ive placed a film i downlaoded Pacific_Rim_2013_BR_720p_x264_ its in the .mkv format, it plays absolutely perfectly on the uno but never plays properly on the duo, it will play fine for about 30-40 minutes, then it will start stuttering, freezing etc and i will get the spinning circular symbol on screen in the top left hand corner, remote wont respond at all, i then have to turn the box off from the back and reboot...any ideas why..?..i was thinking perhaps its the hard drive overheating as its a 3.5" samsung spinout whereas in the uno its a WD hard drive...