movies keep skipping stuck go stuck go stuck go stuck go

ya well i thought it was bad movies i was getting but now ive had about 4 do this to me now so im sure it aint me or the files im getting the files in question seem to stop go stop go stop go stop go and im not sure why about all the other stuff i hs\ave works fine but a few do the skip thing i dunno whats up is it some new codec er sumtin ????????????????????