I've some a similar problem with Rai Uno 16/9 via Dtt channel viewing Europen championship (Italy still alive !
).
A little bit of stuttering with a filtegraph dxva oriented. cyberlink video/sp (pdvd8) with dxva check obviolsly.
evr under Vista Business. Gpu at 10% and cpu less than 10%. some stuttering not to much but present. same ts file on timeshft folder played with mpc-hc same filtergraph don't have the same problem.
With Rai HD Dtt sperimental channel I seen the same your issue the 720x576 info on ts reader pin out. some stuttering also in h264 but less than sd channel