Videos now unwatchable

hi guys i’ve been using my WDTV live now for over a year with no issues, it’s been great, but for the past week large 1080p MKV’s have become unwatchable they will stutter/pause every 5 or so minutes until i stop playback and resume

I am now using SMB shares in Windows 7 pro 32bit

recently several thing have changed in my setup which i will describe now to give you some more information

i went from a ssd for my o/s to a WD Raptor (duw to ssd being sent back for RMA)
i stopped using PS3 Media Server (due to it not supports mp4’s correctly) and am now using windows SMB aharing, any ideas??

i’m going to reinstall ps3 media server now and run some tests

network hardware is pc -> netgear 1gbe switch -> wdtv 

cheers

What brand of netgear switch do you have?