Help w/ Sync Issues, WMC W7, 64b, Assassin HTPC

[gowestwardho]

I have a brand new Assassin HTPC running Windows 7 Home Premium 64-bit and WMC. I mostly experience synch issues when playing back recorded TV shows. In particular the synch seems to get worse when I use the fast forward or 30-second skip commands on my remote. It does NOT seem to help if I pause for a minute and then restart-in-place. The synch seems to get worse and more pronounced as the show progresses. I want to make it clear that I only experience this with recorded TV, NOT with downloaded movies (where it is easy to adjust synch).

I have already removed any 3rd party firewalls, and only enabled Windows Firewall.
I have already disabled all options referencing "Offload" inside the Network Interface properties.
I have already disabled network throttling by changing the registry to ffffffff (Hexadecimal)
My COX provider has tested my signal and optimized it with the correct level filters and/or boosters. And they ran a dedicated line from the house input to the TV Media Center so no other TV's or CPU's are on that run.

I have the following configuration:
Silicon Dust HDHomerun Prime 3 channel Tuner
Onkyo TX-NR509 (HD) Receiver
Logitech Harmony 700 Remote
Sharp LC-70LE734U 70" LED TV
Assassin HTPC with Intel Pentium CPU G620T, 2.20 GHz Sandy Bridge 3MB Cache, LGA1155, 500GB HD, 2GB DDR, 1333 RAM,

I have pretty much exhausted all sources of information that I can find and really could use some expert advice on what is causing this conflict. Thank you.

[Shark007]

most likely, bitstreamed audio is the problem.
go into Control Panel | Sound, doubleclick the active device
on the Advanced TAB, remove the 2 checks in the Exclusive mode section.