Does anyone have tips for avoiding HDMI sparklies?

I get white sparklies (both random pixels and occasional 1 pixel high horizontal lines) when watching DVD's (upscaled to 720p) via Oppo 981 (hdmi). The problem does NOT occur with the HDMI cable run across the room, but DOES occur once I put the same HDMI cable in the wall.

More details:

My plasma (philips 50pf7220) is wall mounted about 10 feet from a recessed set of shelves filled with AV gear.

I initially fished a large bundle of cables between the AV gear and the TV through the wall. The bundle includes HDMI, component, s-video, digital audio out from TV tuner, and L/R/Ctr speaker wires.

There is also telephone/DSL and AC in the wall in the same general vicinity (ie a couple of feet away along the baseboard versus waist high AV cable bundle)).

I did not test the first HDMI cable (monoprice 15ft) before putting it in the wall - I pulled it with the other cables as listed above. At the time I had a junky upscaling DVD player - so when I got sparklies watching DVD's via the HDMI, I figured the problem was either a bad cable or the DVD player HDMI output circuitry.

Trial solution: New DVD player and cable (Oppo 981 with optional oppo 15ft HDMI cable - actually OEM monoprice, larger gauge than my original). Ran the HDMI cable across the floor, over furniture, etc as a test from the Oppo to the TV - worked great, no sparklies. Figured the first cable was bad. So I then fished the new, working, HDMI cable through the wall. However, when I hooked it up, the sparkies had returned. Tried "port-savers" to reduce any possible strain on the HDMI connections - no help.

So despite fishing in this wall twice and buying a new player, I've got the same sparklies.

There are only 2 possibilities:
1) something about fishing the cables damaged them (kink, pulling on connector...)
2) something in the wall is interfering with the HDMI signal (AC power, telephone/dsl, or AV signals)

My diagnositic strategy is as follows:
I'll try shutting off the receiver (ie speaker wire signals) and disconnect the digital audio out from the TV, component, and s-video to eliminate those as a source of crosstalk. Disconnecting telephone/dsl and AC is a little trickier, but I'll try it if the former doesn't work. If none of those work, the cables must be damaged...

Thoughts?
Has anybody else run HDMI through the wall in old construction?

Richard

You could try putting a powered HDMI equalizer at the end, after the cable, but before the display. It might pull out a signal that is clean enough.

It's pretty clear that something in the wall is causing the interference. It may be AC, or some other digital line with a strong signal. When you tried the new cable, did you try it co-located with the other cables that are in the same bundle? If not, it could be any of those, or the AC -- hard to say without turning off the different sources and testing one by one.