Strange slicing when going through receiver (ASRock A75M / Onkyo TX-SR608

Did you try changing your resolution and refresh rate, maybe an automatic update changed something, i have the 608 and it can be picky sometimes. Also, try plugging the BD player into the PC HDMI port on the back of the 608, see if it gives the same issues. The 608 can remember certain settings for each input, and your PC input may have had something changed.

Could the O be doing upconversion or unnecessarily converting the signal from your PC? Seeing as the PC can do your full 1080p resolution you don't need or want the O doing any video scaling, or upconversion as they call it. Once this is confirmed, look at the settings on the video section of your AMD A4-3300 Llano 2.5GHz Socket FM1 65W Dual-Core Desktop APU with DirectX 11 Graphic AMD Radeon HD 6410D and see how it's detecting the O. What settings for scaling is it trying? I know my PJ is detected as Onkyo 803 when I have it connected... maybe there's something there? Oh, and I have my HD4550's CCC set to NOT DETECT connected displays automatically. Seems the cycling of power caused the PC to go see what's connected and reset its settings accordingly. OH, and be sure the CCC's Video settings are set to SMOOTH PLAYBACK... this is a Win 7 OS? Got Aero set ON? It should be. And what s/w are you using to evaluate the picture? Playing WMC, VLC, what? This is a single display setup? And you have the HDMI video and audio devices (both) set as your Default devices?

I like how you've built a small "media-PC" for your TV... I've just repurposed a 2.2GHz Sempron to my bedroom by adding a HD4550 for the display - same model I'm running in my Theatre for my Epson 8350 (1080p) projector.

CCC is AMD's Catalyst Control Center. It's the application you open to adjust the video settings, and such. I'm running Catalyst version 11.5 on my HTPC; although you're using a Llano APU which integrates the GPU - I simply assumed since they're providing a Radeon HD 6410(D) video capability that you'd be using their Catalyst drivers. Yes, no?

I looked into your Mitsu and they can be quite tempremental... I found an Owner's Manual here and it spouts off about not connecting a PC to the HDMI inputs offering the DVI as the computer input saying something about the HDMI inputs and how they "process" video motion signals... I can't believe the PC wouldn't conform to the same standard. It seems the Mitsu will interpret all formats including 24Hz, 50Hz (European), an 60Hz at 1920x1080. In fact, this is listed in Appendix B for both HDMI and DVI inputs! Again, as a test you may want to see if there's any noticable difference between these two - it be good info if you could report back