I just installed a PVR-150 in my myth box last week, and got it working "o.k." with an older video card that I had in the machine previously. The video during live TV playback was a little herky jerky, though, so I swapped out the old GE Force4 MX440 64MB PCI video card with a brand new Nvidia FX5200 256MB PCI video card (from PNY). After I rebooted my machine, I went to watch live TV and all I got was 15 seconds of blank/black screen (and no sound) and then I was kicked back to the main myth menu.

I am really starting to think that my processor it too week for live TV playback, and perhaps even for DVD playback. I originally thought that if I upgraded my video card to the FX5200 256MB, it would cure my problems, but the "upgrade" did not seem to help at all. In fact, I only seem to be getting this "black screen" problem with the FX5200 card (and not with the old video card). I did a little bit of testing with this PC the following weekend in Windows XP, and tried to play some ripped DVD (VOB files); but the processor was pegged at 100%. This is what led me to think that my CPU is too weak.

Here are my machine specs:
AMD Athlon 850
400MB of RAM
Hauppauge PVR-150 MCE edition (model #1062)
PNY Nvidia FX5200 PCI video card w/256MB of ram (the reason I am using a PCI video card is that this old mobo only has a 2x AGP port)
PCI ethernet card
PCI sound card (some old yamaha clunker)
PCI USB2.0 card
IDE hard drive and CD-RW