Same problem here just after updating from 10.04 to 10.10 today.
I'm using Dell D430 laptop.
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
The second monitor is activated but it's like the resolution is wrong. I can see the mouse on my second monitor but just on the edge of the monitor. Can't move it around on that screen.
I just noticed that screenshot tool doesn't detect the second display as well.
I've changed back and forth between the monitors in System > Preferences > Monitors.
They all detect, and all have the correct resolution, i can use one at a time and both work well.
xrandr -q
Code:
Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 4096 x 4096
VGA1 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 473mm x 296mm
1680x1050 60.0*+
1280x1024 75.0 60.0
1152x864 75.0
1024x768 75.1 60.0
800x600 75.0 60.3
640x480 75.0 60.0
720x400 70.1
LVDS1 connected (normal left inverted right x axis y axis)
1280x800 59.8 +
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
DVI1 connected 1680x1050+1680+0 (normal left inverted right x axis y axis) 434mm x 270mm
1680x1050 59.9*+
1600x1200 60.0
1280x1024 75.0 60.0
1440x900 75.0 59.9
1280x960 60.0
1152x864 75.0
1280x720 60.0
1024x768 75.1 70.1 60.0
832x624 74.6
800x600 72.2 75.0 60.3 56.2
640x480 72.8 75.0 66.7 60.0
720x400 70.1
TV1 disconnected (normal left inverted right x axis y axis)
Bookmarks