MCE 2005 Live TV freezes

I have a Dell Dimension 8400 on MCE 2005. It's run fine for years. Around May 23, it stopped recording. Although Windows reported the tuner card was fine, MCE couldn't detect the card.

I replaced the card with a USB dongle and reconfigured. The live tv image in the preview window and Full screen would play for between 5 seconds and 2 minutes before freezing. MCE still funtioned properly (i.e. it wasn't frozen, just the TV image was). Ordered a REMAN ATI PCI card from Dell and it's doing the same thing.

Yes, I have updated the drivers, including my display video card. Any ideas? Anybody?