I am lost with this one folks and some help would be appreciated.
My secondary display is DVI out to HDMI in to an LG LCD HDTV. However, all I see on the secondary display is the wallpaper unless I drag sideways. Why don't I get a full screen preview on my LCD?
I originally had a firwire out to a canopus and then rca plugs straight into an old CRT TV and the full screen preview worked all the time.
Why does it not work by simply using the dual output of the graphics card to the HD display?

I'm sure you have set the properties correctly for this ?
Right click external preview icon and set to windows secondary display.
That was all I had to do on my setup. There may be other settings in there as well.
Good Luck

Hi Jim, I have no idea what I did but it is working fine now. Perfect picture at Best Preview Full.
Thanks for taking the time to reply.

Just made some monitor changes due to a faulty dell (which was a 2nd monitor) and I now have a Sony 20" HDTV and one Dell 20". I want to use the Dell for normal windows and have the Sony display full screen preview. The Dell is driven by DVI-DVI and the Sony from DVI-HDMI

I've enabled the use of a dual display on the Nvidia Ge Force 7950GT and its outputting 2 signals fine. I get the normal options of spread across both screens etc. I'm getting the output on the Sony but when I enable Windows Secondary Display in Vegas Preview Setting I get 'Device Unavailable' so just end up the same screen on both monitors.

Any ideas what blindingly obvious thing I've overlooked?

Stuart

cracked it. Nvidia driver update solved the problem!