setting resolution for LCD TV(vista keeps changing)

hi all,
i have windows vista home premium, on a amd 3500+,with raidon 550 256meg
graphics card(after a painfull location and installation period! installed
now ggrrrrrr) 2 megs ran, 150 gig sata and 200 gig ide, used in my loungeroom
for WMC,im running through the graphics port DVI to HDMI connection to my LG
42" LCD with 1324*768 dpi(hdmi channell)

when i loaded clean vista OEM,the screen resolution auto tuned to 1324*768
and a lovely widescreen without 'streaching' then after A reboot went to
1024*768!
so i loaded graphics CD,and nvidia made it go back to 1324*768!,then 1
reboot, back to 1024*768!!! and i went through'advanced' in screen
resolution, then to 'show all resolutions, nothin over 1024*768!

so...i tried updating driver...nada.

help?