Unable to enable dual displays

Question

I am running an almost-fresh version of Ubuntu 12.04 on my old Dell Inspiron 710m laptop. I had to re-install yesterday due to a different display issue. I wasn't able to directly reinstall 12.04 because my system can't handle the PAE kernel. Instead I installed Xubuntu 12.04 and then installed the Ubuntu desktop.

Now I am unable to enable my dual displays. I want to use the laptop screen and an Asus VE228D monitor attached to the VGA port.

Ubuntu sees both of them (both via xrandr, below and Displays). I can set both to 'on' in displays, but when I hit Apply, only one shows the desktop (the other remains black). There's no error message given, but my mouse won't scroll far off of the visible screen, suggesting that the the desktop isn't being extended, either.

XXXX@mel:~$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 2048 x 2048
LVDS1 connected (normal left inverted right x axis y axis)
   1280x800       60.0 +
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080      60.0*+
   1600x1200      60.0  
   1680x1050      60.0  
   1280x1024      75.0     60.0  
   1440x900       59.9  
   1280x960       60.0  
   1152x864       75.0  
   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  
DVI1 disconnected (normal left inverted right x axis y axis)

I have an old Intel video controller, here's the extent of what I know about it.

XXXX@mel:~$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 82852/855GM Integrated Graphics Device (rev 02)

Prior to the reinstall, I was able to have dual output with this same setup, same graphics driver, etc.

I would love to hear any suggestions about what to try.

I've seen people post this information from lshw as well, so here it is (in case it's useful).

XXXX@mel:~$ sudo lshw -C display
[sudo] password for XXXX: 
PCI (sysfs)  
  *-display:0             
       description: VGA compatible controller
       product: 82852/855GM Integrated Graphics Device
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 02
       width: 32 bits
       clock: 33MHz
       capabilities: pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:11 memory:e8000000-efffffff memory:e0000000-e007ffff ioport:1800(size=8)
  *-display:1 UNCLAIMED
       description: Display controller
       product: 82852/855GM Integrated Graphics Device
       vendor: Intel Corporation
       physical id: 2.1
       bus info: pci@0000:00:02.1
       version: 02
       width: 32 bits
       clock: 33MHz
       capabilities: pm cap_list
       configuration: latency=0
       resources: memory:f0000000-f7ffffff memory:e0080000-e00fffff

A few additional comments:

1. Fwiw, I logged into an Xfce session to see what the situation was there. Xfce showed the extended desktop across both displays, though changing the display resolutions caused problems there (overlapping desktops, black regions outside the virtual desktop).

2. I try to mirror monitors through Ubuntu, the desktop only shows up on one, the other remains blank.

3. Dual display with extended desktops works fine on my Windows partition (though I can't get as high of resolution on the large monitor as I want).