I just got the same card, and its doing the same thing. Studdering occationally, as if my system is doing hard work, when really its just idle.
I can tell something is happening because any audio playing will studder as if slowing down momentarily, as well as mouse speed studdering.
I'm certain it has nothing to do with drm as suggested above, as it affects entire system, its just more noticable with audio playing (including game audio).
i read people having problems with the drivers (http://www.newegg.com/Product/Product.asp?Item=N82E16833127213), and that "The chipset is made by atheros, which also is in the wpm7000 by linksys" (from post in link above), but i can't seem to find the drivers for a wpm7000 by linksys, if it even exsists.
this is really a pain in the ***.
uninstalling the card gets rid of the problem, and it comes back when i reinstall it.
its also auto starting the d-link wireless connection manager twice, so that two green bars appear in my notification area.
i had a netgear wpn 311 who's drivers kept crashing to blue screen randomly, which is why i thought i was "upgrading" to this d-link card and router. so im not having the best of luck with wireless.