Display shifted right maybe 10px

[networks1 at cox.net]

I am setting up a new FC12 system using a plasma monitor for the display, and Nvidia GeForce 8400 GS as the vid card.  It's working but the display is shifted maybe 10px to the right of where it should be.  I researched this and tried various things like adding explicit horizontal/vertical scan ranges, display size, etc., but the problem persists.   Nothing seems amiss in the Xorg log.  The relevant parts of xorg.conf are below.  Can anyone advise me how to fix this?

Thanks..............Steve

Section "Device"
	Identifier  "Videocard0"
	Driver      "nvidia"
	Option	    "AddARGBGLXVisuals" "True"
EndSection

Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Panasonic"
        ModelName    "TH-42PHD6"
        HorizSync    15-45
        VertRefresh  24-60
        DisplaySize  920 518
EndSection

Section "Screen"
	Identifier "Screen0"
	Device     "Videocard0"
        Monitor    "Monitor0"
	DefaultDepth     24
	SubSection "Display"
		Viewport   0 0
		Depth     24
                Modes     "1024x768"
	EndSubSection
EndSection

Section "Extensions"
	Option	    "Composite" "Enable"
EndSection