Forgive me brothers, but you where right and i was wrong.
And the sinner was..... ----> THE AHCI DEVICE DRIVER <----.
As you can see i have a Nvidia chipset on the board of my HTPC. One year ago i had some bad issue with the Nvidia AHCI drivers (problems with Nvidia IDE/SATA drivers are well known since the frist chipset release years ago).
So my solution a year ago was to use the standard Microsoft AHCI drivers. They worked so far, but THOSE DRIVER WERE THE REASON FOR MY CURIOUS ISSUES WITH MP.
The explaination why the stopping of live TV with VMC did not happen was because VMC does not use the harddisk during live TV without timeshifting, but MP always uses the harddisk!!!
Those Microsoft drivers cause the harddisk timeout... and MP live TV suffered from it.
I had good luke that Nvidia release some new drivers without the issuse i had in the past.
I install the new Nforce driver package and EVERTHING was fine.