Flaky Dual Display

Hi.

I'm having a problem with a dual display system with windows opening in
flaky locations. Some applications open on the wrong display, as do most
dialogue boxes. Many applications when full screened span 20 or so
pixels into the other display, which can only be fixed by changing the
Snap window edges setting to something different - doesn't seem to
matter much what. Very annoying behaviour.

I have a Clevo M7U laptop with a nVidia GeForce Go 7900 GTX adaptor,
running the 8.4.2.6 version of the driver. The laptop screen resolution
is 1920 x 1200, but running at 1280 x 768. I have it configured for a
dual monitor display with a 1440 x 900 17" TFT Monitor (Chimei CMV
938D). The nView Desktop Manager is set to dual view, with windows able
to span displays (tried them with the other setting, no difference),
opening applications on the external display, repositioning dialogue
boxes to the cursor's display and not Snapping window edges.

Can anyone suggest a solution?

Edwin