I had this issue, couldn't get through a movie to save my life without it freezing up and coming back. Solution was to stop letting windows 7 put my hard drive to sleep. (not sleep mode, windows 7 cuts the drive after a while when it thinks you're idle or whatever - changing that setting, it fixed it)
I run windows 7 64bit and after a while my system has been running it periodically every 4-5 minutes freezes for 1-2 seconds causing everything to freeze and if i'm playing a video or music it kind of stutters and creates a buzzing sound then it kicks back to normal again. I have checked the task manager and there's no…
Might be your hard drive spinning down (that is if you aren't using a SSD...). I had this problem with Vista, anyway: http://www.neowin.net/forum/topic/983350-turn-off-hdd-spin-down-windows-7/ Hope that's it. Good luck!