Under Process Explorer, I noticed that
System -- and occasionally
Interrupts -- are taking between 5% and 20% CPU constantly, for hours on end. This is resulting in weird video playback problems. (Audio files have 'gaps' and YouTube videos have pauses in them.)
This problem has been happening for a while. Sometimes, a restart fixes it, IIRC. I also recently upgraded to a 1920x1080 monitor... But this shouldn't have any affect on audio. I also just disabled ReadyBoost (which I also got recently).
I killed PeerBlock and uTorrent, and this still continues to happen; previously, killing them was enough to get my CPU back down to ~0%.
My CPU temperature is ~55 C and my HDD is at <40 C.
So it is uTorrent's fault (or PeerBlock or Comodo).