The ABVB's VGA monitor output is always active, whether a monitor is connected or not. With AVOption software, use of this monitor is supported for playback of the floating movie window only. Displaying other windows (plug-in, mix, edit, etc.) on this monitor can result in -6042 errors. If this port is not being used, it is possible that one or more Pro Tools windows (or small fractions of windows) are appearing on this monitor, even though there is no monitor connected. Use the Monitors & Sound Control Panel to arrange the monitors so that the ABVB monitor is situated caddy-corner to your Macintosh monitor(s). Do this by dragging the ABVB's monitor icon so one of its lower corners is touching one of the Macintosh monitor's upper corners. This way, none of the Pro Tools windows will accidentally be displayed on the ABVB monitor.It is also recommended that you designate that the monitor connected to your Macintosh's video card is the "startup" monitor by dragging the menu bar icon to the proper monitor icon. Use the Identify Monitors button to determine which is which.