hi, just a quick update.
sorry for not including all the info
ive tryed Enhanced multicore support for H264 HD content on and off, have also tryed all 3 video engines and have reinstalled a load of stuff like K-Lite Codec Pack 4.8.0 Full with no luck, anyway ive got it to a point were i think its fixed ..fingers crossed
the problem was the turn of display option under power settings, ive have to set it to never, ive also tuned of my screen saver, which was aurora ..im now 45mins into a avi running on Tsmuxer
also the original problem was with avi, mkv files etc but all looks fine now. so will post up some more info if inf-act its not fixed my doing this ..
ps forgot to add my graphics card to the orginal pc spec..it a gtx280 if other people are having this problem.