Video downloads for one minute, then stops

I'm having trouble watching streaming video on my macbook pro, but not other computers on my network. About a minute of video will be downloaded right away, then it says loading, but never seems to actually load the rest. This is happening on Netflix, youtube, other sites that have embedded video. Is there some kind of setting on the mac that is affecting my ability to watch streaming video beyond 1-2 minutes in length? Thanks for any help you might be able to provide!
Maya