Windows 7 - Plasma EDTV + HD5570 Need help.

Hi,
I am very confused
I have a plasma EDTV LG model 32pc5rv ( no money for upgrades, right now) and I bought the HD5570 fOr my HTPC with windows 7 x64 ultimate.
the Native resolution from TV is 852x480, but it accepts 720p and 1080i signal
Well, I plugged a HDMI cable from graphic card into the TV and after that first screen, any image appears (no signal message). So, I plugged the RGB cable from graphic card into the VGA input TV and the desktop screen appears normally.
But when I restart the windows the problem keeps up. So the windows just starts with the VGA output, and after the desktop screen appears I plug the HDMI cable, just like that the HDMI works.
I think its a resolution problem, maybe the hd5570 hdmi output dont accept 480p (the native resolution from TV)
What resolution windows 7 load ?
I dont know what to do, because there are three variables: TV, graphic card and SO.

Sorry my awful english

Thanks

welcome to the forum, and firstly dont apologies im english and i understood you

I think the standard windows loading resolution is 800x600, as thats the default resolution when you dont have video drivers.

I think youve already guessed the problem, your tv doesnt support the native resolution.

im not sure but you could always try updating your video drivers, or having a play in the catalyst control center.
as it has a section for HD TVs,

Thanks for reply !

Well, In the Catalyst > desktop properties> settings is marked: HDTV 648p; 720p; 1000i; 1080i, but why it works fine when the desktop screen appears ?

If I install another SO like linux ?

Thanks !

well like i said its probably the start up resolution is not a supported one by your TV. And maybe, but if it starts up in the same resolution as windows then youll be back to square one.