I had a 17" (left) and 33" (right) setup where the 33" was used only for 3D CAD. If I turned the 33" on the system recognized it was activated and the cursor could travel across both monitors. If I turned the 33" off, the cursor was limited to the 17", as expected. Both were running off an NVIDIA P400 add in DisplayPort board.

I reconfigured with the 33" (left) and a 42" (right) but now the system acts as though the 42 is always on even if it isn't. When the 42" is off, the cursor disappears from the left monitor and sometimes apps show up on the turned off monitor only to be seen and moved if I power that monitor on.

The 33" is a DisplayPort unit and the 42" is an older HDMI monitor. I pulled the NVIDIA board out and both monitors are running on the mobo's ports.

Why can't the system recognize when the 42" is off?