Going to stop for the night and think on this, going to also leave my switch and router unplugged overnight incase it is issues with them causing network packets to be dropped and showing up as those errors.
I use no codec packs, I only install matroska and then if needed (for 2 speaker setups) AC3 filter, I've always done it that way and more than likely always will. It seems like I have always run in to a ton of trouble with those.
I took my Samsung S23A750D and hooked it both straight hdmi to the HTPC and then to the receiver and seen video speed ups, stuttering and jumping just as before, tv threw the same error hooked straight to that display too... but the HD Homerun is on the same physcial 5 port gigabit switch as the HTPC then uplinked to a 8 port gigabit switch. I have to use a switch there as I have the receiver, HTPC, Xbox360, Slingbox and a HD Homerun (xbox is unplugged at the moment lol) all needing wired, then my 8 port switch is hooked to the 5 port in the living room, and another 5 port in my sons room (PC and Xbox 360), my daughters PC, the home server, my main PC, my arcade machine and finally to my router.
I tried 11.8 drivers no luck, uninstalling playready as suggested somewhere else, updating my NIC drivers, flushing DNS, NBTSTAT -R and resetting the winsock, nothing has helped.
I'm on my main rig in my bedroom now and am seeing the skipping and jumping on bluray playback from the server here too, I already rebooted the server thinking that might be it, but that didnt help. The server is a fresh setup (well been up for a month, and was workign before) of WHS with 4 2TB drives and 1 1TB, disk performance was never outstanding with WHS but in the past I have been able to watch a HD movie in three rooms simultaniously with no problems.
Hopefully this is just something stupid like a bad main switch causing collisions or something.