DragonFlyBSD

On my laptop, if I switched to my dock connected setup like this:

xrandr --output HDMI2 --auto
    xrandr --output LVDS1 --off 
    xrandr --output HDMI3 --off
    xrandr --output VGA1  --auto --right-of HDMI2

trying to switch it back to LVDS1 like so

xrandr --output VGA1 --off
    xrandr --output HDMI2 --off
    xrandr --output HDMI3 --off
    xrandr --output --LVDS1 --auto --primary

yields black screens all round, the computer is not accessible.

Video Hardware:

vgapci0@pci0:0:2:0: class=0x030000 card=0x21fa17aa chip=0x01668086 rev=0x09 hdr=0x00