Weird resolution problem with my tv :/

[ZaO]

I have a tv that states it does 1080i. So here's what happens...

I can play games on it at 1920x1080 and they run fine (bar a bit of ghosting but I guess the response time probably just isn't that great). With vsync I am getting 60 fps.

However, when I am on the desktop and wanting to set the resolution it recommends that I use 1280x720 @ 60hz. When I set it at any resolution above that I am restricted to 30Hz and the screen is kinda flickering with a lot of ghosting when I move windows around. It's only the desktop that's like that though (I am setting it at 1920x1080i btw, not 1080p.). When I am watching a video or playing a game it appears to be fine.

So what I'm wondering is why is it flickering and ghosting real bad on the desktop? Is it because it's using a 30hz refresh rate? If so then why can I run games at 60hz?

Cheers. Hope someone can help me figure this out...

Edit: Ah you know what. I did a test with my monitor on 29hz and the screen flickers just like the tv. So I guess I half solved the issue. So now I just need to figure out why on my tv games can run at 60hz but the desktop can't?