I cant keep my second monitor detected in 12.04

Question

On my work machine the second monitor, connected to the DisplayPort (DP1), is flickering into and out of existence. I'm only running onboard graphics, i.e.:

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)

Here's xrandr when Ubuntu is NOT detecting it:

$ xrandr -q

Screen 0: minimum 320 x 200, current 1440 x 900, maximum 8192 x 8192
VGA1 connected 1440x900+0+0 (normal left inverted right x axis y axis) 408mm x 255mm
   1440x900       59.9*+   75.0  
   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  

HDMI1 disconnected (normal left inverted right x axis y axis)

DP1 disconnected (normal left inverted right x axis y axis)

Here's xrandr when ubuntu IS successfully detecting it:

$ xrandr --query

Screen 0: minimum 320 x 200, current 2464 x 900, maximum 8192 x 8192
VGA1 connected 1440x900+0+0 (normal left inverted right x axis y axis) 408mm x 255mm
   1440x900       59.9*+   75.0  
   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  

HDMI1 disconnected (normal left inverted right x axis y axis)

DP1 connected 1024x768+1440+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0* 
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  

When it's detected it appears to work - background, mouse movement, etc. and then flickers back into oblivion a short time later. It is (or is not) detected by Displays depending on whether or not it's in existence at that time.