Hate to piggyback onto someone else's thread, but I'm having the same issue though usually it's the audio that drops out. I have an AMD HD6670 in my Windows 7 32 bit HTPC and I'm getting audio dropouts and ocassional video dropouts switching back to it from any other source. I've set up the computer never to sleep, but as soon as the AVR switches to either Cable or Bluray, the sound won't return when I come back to my computer.
I have had this problem running CCC 12.6 beta, 12.7 beta and 12.8 official. It was originally much better with 12.6 beta until I changed out receivers from an HK AVR 2600 to an Onkyo RC-HT203 (I needed the 7.1 from the HK to go down in my screening room as soon as it's complete.) Now that I've changed the receivers it "dependably" loses sound every time I return to computer in the receiver.
I've tried 3 different EDID override attempts but none of them fixes this issue. 2 of the three did cause me to lose video completely until I did a cold reboot. I was debating trying the EDID override once again when I ran across this thread.
Since the older DVI Detectives are cheaper than the HDMI Detectives, could I use one, or will I lose the sound feed that goes on the HDMI feed as well?