I don't know if this is a bug or not, but a workaround is to simply restart X (Ctrl-Alt-Backspace) once you have switched the monitor on. When X restarts, it will use the higher resolution ... at least that is how it works for me.
I don't know if this is a bug or not, but a workaround is to simply restart X (Ctrl-Alt- Backspace) once you have switched the monitor on. When X restarts, it will use the higher resolution ... at least that is how it works for me.