Display resolution issue on 12.04 with external display on laptop

[Chris Green]

We have just upgraded my wife's Dell Vostro v13 laptop from
10.04 to 12.04, it all works OK except that it doesn't work so well with
an external monitor as it used to.

What happens now when an external monitor is plugged in is that the
laptop screen runs at 1366x768 (as it should) but the external VGA
screen runs at 1024x768 and only shows the LH portion of the full
1366x768 screen.

It used to work fine on 10.04, when the external monitor was plugged in
the internal screen was disable and the external one ran at its native
resolution 1680 x 1050.  Now what happens is that the internal screen
contnues to run at 1366x768 and the external one runs at 1024x768 and
shows only the LH portion of the full screen.


Any ideas for a workaround/fix to get the external monitor right?

-- 
Chris Green