Windows XP Not displaying fully on 1440x900 resolution.

After setting up a Y-Cb-Cg connection between my Nvidia 9600 and my Standard-Def TV I had to fiddle around with the resolutions in order for the display on the TV to be correct/ at kleast viewable, I corrupted my Screen drivers. 5min later new driver installed, but it seems like windows XP will no longer resize my desktop canvas to its 1440x900 resolution. Syncmaster 923nw. Games resize the canvas correctly but not XP. Please I have tried near to everything to get windows to fill my screen. Everthing simply seems top open behind the 0.5 inch black line at the top of my screen. Monitor setting are 1440x900, Windows Dislpay Properties = 1440x900, Nvidia Panel= 1440x900, but stil windows refuses to display fully on this resolution. Pleas ehelp