Playing movies over a network = Slow device

I am experiencing this problem, all the movies in 720p (medium size 6 ~ 8GB) are slowly leaving the unit and causing dyssynchrony in the legend (forward and back arrows the control does not solve the problem). Some episodes of series are also the same problema.O WDTV connected to my pc with a crossover network cable to a dedicated network adapter.
If a USB device for excute the system plays to perfection.
some examples of files that are experiencing this problem:

* Horrible.Bosses.EXTENDED.REPACK.720p.Bluray.x264-TWiZTED
* I.Am.Number.Four.2011.720p.BRRip.XviD.AC3 TIMP-
* Scott.Pilgrim.Vs.The.World.2010.720p.BRRip.XviD.AC3-ViSiON

* Two.and.a.Half.Men.S09E01.REPACK.720p.HDTV.x264-FQM

a friend played these files on your WDTV and functioned normally.

Does my device with this problem?

* an excuse by the English translator of google *

This looks like a choke point in your network, the files play great if they are in a USB drive?

Can you provide more information of your network setup?

when I play the files on a usb pen drive (flash drive) the execution is perfect.
I have a gigabit network card (pci) dedicated connection to the WDTV is made by a crossover wire (WDTV = T568A  / / pc = T568B) of 5 or 7 meters (made by me, new).
When the network card already switched to other, all new, and all had the same performance.

more information ?