Hello
I have the exact same problem. Allready had an Android TV stick returned (MK808) because thought it was a hardware problem but I recently bought another (MK802IIIS) from another retailer and the problem is still there.
My tablets don't have any problems so I assume that it is a support problem as audio01 refers...
Most of my files (opened directly on BS over lan - by the way thanks a lot for that functionality, in my house it's great because my PC is on one side of the house and the TV on the other) open like this - (
https://www.box.com/s/gt4gje4cgfd4z0grm85y) or just stuttering.
I don't really know if this is really the problem but since audio01 had this post here with hardware similar to mine I think our problem's the same...
Thanks
Bye