[Apothis]

I dont have any 1080i material to test with, but I can tell you that MPEG2 is not hardware accelerated on this box, so playing with that wont help. Incidentally, do you get the deinterlacing option to become selectable on yours? I tried an SD interlaced clip for someone the other day, but couldnt get the deinterlace option to become selectable no matter what I tried.

Yes, if you disable both acceleration options you should be able to select deinterlacing (I think you can also have one of them enabled and still get deinterlacing options but I'm not sure which one).

That was the first thing I tried (disabling both). No matter what the setting, I couldnt get the deinterlace option to become active.