EA / C&C games - Jittery sound?

[Mario]

Well i have both Command and conquer 3 w/Kanes wrath and Red Alert 3, and both of them seem to have really jittery sound, even on the menus, it seems to stop and start in quick succession, and be really delayed, this only happens in these three games so it isnt hardware related, i can also run all the games pretty much perfectly and still does it when ive set them to lowest settings.
It isnt my disk drive because i downloaded RA3.
Help?