HELP please, movies freeze, size issue??

I am playing movies over my network. It seems that any of the files that are over 2GB freeze around the 1hr 20 ish minute mark. It happens on all of my movies that are larger in size. It happens on Sapphire and XBMC as well. I have an extremely fast wifi connection on the 2.5 or 5.0 GHz N band. I’ve tried disabling H.264. I’ve smart installed and rebooted.

Is there something I can tweak or correct? Would connecting thru ethernet correct this?

I really do not want to have to break these up into smaller files. Movies that are over 2 hrs would be in at least 3 or 4 parts. Can somebody explain what the problem is? Is there a good solution? Any help would be truly appreciated.

no change with ethernet hook up