720p /1080i in Theater Mode with 3850?

I've got an ATI 3850, and I'm running dual display, one to my 19" LCD via DVI, and the other to my 50" plasma via component. In regular desktop modes the 50" displays a 720p signal perfectly. When I try to watch a movie fullscreen (in theater mode) it always reverts to 480i, no matter what the resolution of the source is. I've tried this in both "clone" mode, and "extended" mode. I've tried MPC, Zoom, WMP10, and a few others. The only way I can watch fullscreen 720p or 1080i is to turn off theater mode and go fullscreen on both displays. Is this a limitation of the drivers/hardware, or just something I'm not doing right?

I really want to be able to have HD vid playing on the 50", while still having my 19" open to the desktop. It's the only reason I bought ATI, as I had an 8800GT which didn't support that feature.

Nobody? I can't possibly be the only person trying to do this...

Wow, 100 views and no love. I was really hoping someone else had this same problem.

Has anyone gotten Theater Mode to display on the second monitor with more than a 480i resolution?

Theater mode automatically displays any video fullscreen on the second display. This eliminates you having to move your video over to the extended desktop and fullscreening it. Problem is, no matter what your desktop resolution is set to, the output to the tv lowers itself to 720x480. I haven't been able to find any kind of workaround, and I've tried a lot of third party tweaking apps with no success.

It's very handy for video editing.