Pcie 1x tuner in 16x slot: PC won't shutdown :(

[TheFamilyMan]

I recented replaced my ancient Ati Theater 550 PCI with a Ati Theater 650 PCIe, mainly so I can watch decent quality OTA digital TV on my computer. I like these cards because their analog video capture is first rate and their tuner section is mighty fine as well. So anyways, my mobo has two available PCIe slots, a 1x and a 16x (which only supports 4x rate). When installed in 1x slot, the card is right next to my gtx 560ti; and I mean right next, 1/8" or less clearance. But if I use the 16x slot, the card works perfectly except the computer will not shutdown. Windows seems to finish up and the monitor signal drops, but the system won't power off. On restart, windows comes up as if nothing was wrong. I've tried reinstalls of both the drivers and the card to no avail. The card/windows works fine with that 1x slot, but it proximity to that monster TFII cooler makes me nervous (one of its fans barely clears, ~2mm, a chip on the back of the tuner card). I've made sure that both those cards are secured as solidily as normally possible. I've also flashed the bios to the latest rev and used the latest chipset driver to no avail. Any ideas?

One interesting side note, a Windows 7 mediaplay service grabs a resource of the Theater 650 card that prevents video capture software, such as VirtualDub, from using the card. That mediaplay service has to be killed before VirtualDub works properly (other captures apps also behaved in this manner too). For my needs the 650 Theater performance is excellent (considering too that I got one new on ebay for $30). With its two tuners (analog and a digital) I've been able to connect one of my VCR's antenna out to the card's analog, so I can watch those ancient tapes through mediaplayer as if it were yet another TV channel.

EDIT: CRAP! macrovision protected tapes are also 'zapped' by the antenna input!
All I want to do is to be able to watch them without using a bonafid TV, no interest in copying