Help! Popping on my speakers

[Arr MiHardies]

Ever since I upgraded my home theater in may, I have been experiencing popping on my speakers. They happen at seemingly random intervals, on a random speaker. I can go for hours without hearing any popping sometimes, others I cant go for more than a few minutes.

My original setup was thus:
sony 57" rear projection tv (forget the model number)
onkyo TX-SR603X receiver
onkyo 5 disc dvd changer
scientific atlanta 8000HD cable box
and an
Apple TV
all connected to my reciever and tv via Monster component video cables.
These were originally connected to an APC power strip

my new setup is thus:
Samsung 52" LCD tv (newer model, dont have the number handy)
harmon kardon receiver
samsung bd-1200 blu-ray player
scientific atlanta 8000HD cable box
and an Apple TV

the blu ray and the apple tv are connected to the receiver via monster 1000 HDMI cables, the cable box via component video cables (my receiver will upconvert component to 720i hdmi), and the receiver to the tv via a monster 1000 M series cable.

Of course, I immediately suspected the new receiver to be the culprit, which I promptly exchanged, not only for the popping, but because it would not upconvert analog video to hdmi. I ended up getting an Onkyo TX-SR605. It only upconverts to 720, but that is better than nothing, and the only ones I saw that could upconvert 1080i were far out of my price range.

Originally I used the same apc power strip to power this setup, but when I experienced the popping, I went and got a monster power 1600 power conditioner. But the popping continues.

Being a computer tech I know how to do troubleshooting, and I've done quite a bit of it, but at this point i am rather stymied. I have since moved to a new home, with in ceiling speaker, so that rules out the speakers and their wiring. I got a new entertainment center when i got the setup, I thought that maybe the power cables got bundled too close to the speaker wire, but when i moved, I moved that center to my new loft, and got a new ent. ctr. for my main viewing area, giving a completely new wiring arrangement. I have each of the following components, in turn to my secondary setup, including the blu-ray player and the cable box. I have tried switching out my hdmi cables for component cable to see if it might be an hdmi problem, and while the popping was noticeably lower in volume, they still continued.

One thing I did notice was that the popping was always more frequent and louder when my air conditioner was on, in both my homes. However, I still get occasional popping even when the AC is off.

Can anyone offer any help at all with this problem?? I never had this popping before upgrading my equipment.