Matthew Toney:
Mykroft: Do you (or did you) happen to have an X2 CPU in the machines where you've seen the problem?
Actually, I do have an AMD X2 CPU in that machine. I can't say what kind of AMD drivers I have installed because I have no idea. I did at one point turn off the Cool & Quiet feature of the CPU, but that was in response to other VMC issues I was having with CableCard. Unfortunately, I abandoned my CableCard setup and went back to DirecTV because using CC in VMD really blew and ultimately never worked correctly for me.
I do have my VMC setup now on an older DirecTV STB to record some shows as a backup to my DirecTV HR20 DVR, and so far I can say that I haven't seen any re-occurances of this problem.