Problem with HDMI Cable


In Runtime
Hey guys,
I have an HTPC which has previously been running HDMI to my TV just fine. I had normal speakers plugged in via the sound card.

I recently got an Xbox 360 and so had to get a second HDMI cable. I used the NEW cable on my HTPC and put the old one on my Xbox 360.

I also plugged the speakers into my TV, and changed the default sound output on my PC to the HDMI, so that all the sound from all the devices go to the speakers.

Everything seems to work just fine except for high definition TV channels (digital channels work fine - haven't tried blu rays or HD movies yet) - I get a "Video Error" in media center, claiming i've not the codecs etc.

Any thoughts?