I just set up an HTPC, and I'm still occasionally getting digital static / pixellation (a flicker every 30 seconds or so). I'm not sure how to go about finding the cause. The source is Time Warner cable (unencrypted local channels)
via an HDHomerun dual tuner,
then to a wireless n adapter on my HTPC,
then HDMI output from my computer (from onboard HD4200 graphics) to my 720p plasma TV.
You have to eliminate the possibilites. Remove a device from the link one at a time until problem goe away or go from the cable to TV and start adding devices until problem returns. Don't assume the cables are good either.
Or take HTPC direct etc....
I have been taking that approach, and I have eliminated a few things. First of all, it's not the signal, or my splitters. My computers can show DVDs just fine (don't have Blu-Ray yet), so assume it's not the graphics. So, at this point I'm assuming it's the router. Our Linksys router is rated at 54 Mbps. From what I've been reading, streaming HD video (especially fast forwarding and rewinding) requires a router that can handle 300 Mbps. So, I think I'll be ordering a new router. Even if it doesn't completely solve the problem, it will certainly speed up our web browsing.