Permanent VGA Signal Loss when Monitor Disconnected (Mobile 945)

I'm running a single-board computer (x86, XP SP3) that uses a Mobile 945 as its graphics processor.  There are two displays available: One VGA and one DFP.  The DFP is implemented by the board's manufacturer, but it is not accessible by us.

The basic problem is that our customers may not normally have a (VGA) monitor connected.  That is only necessary for configuration and troubleshooting.  What we find is that if the system boots without the monitor connected or even if we disconnect the monitor after the system is running, when we reconnect the monitor it remains black.  It appears as if the graphics subsystem does not detect its presence.

Naturally, we want to find a way to always keep the VGA port alive (or at least have it enable when a monitor is connected).

Device Manager shows two display adapters and five monitors (two DFP and three VGA).  This appears to be normal.

We have tried the following approaches to solving this problem.  None of them work:

- Using hotkeys (<CNTL><ALT>1) to enable the monitor after it is (re-)connected

- Disabling all the DFP's in Device Manager (we even tried disabling one of the display adapters)

We had some success when we configured the driver for Multiple Display/Intel(R) Dual Display Clone.  In this setup, we can disconnect the monitor and the VGA output is active when we reconnect.  The problem is that this configuration does not persist after a reboot (the system reverts to the single-monitor configuration).  One other annoyance is that the graphics driver will not allow us to select the native resolution of the monitor.  It appears to force both VGA and DFP to use the same resolution (which makes sense in this case).

Attempting to force the desired mode by editing the registry does not work.  The system seems to reject the new values.

Is there a set of registry modifications or an application that we can auto-run at startup that will solve this problem?  It would be ideal if the application that configures the driver (igfxcfg.exe) could be run with command-line arguments that would set the desired configuration.  We could set up a "scheme" with the desired options and invoke that.

Here is the output generated by the graphics driver utility:

Intel(R) Graphics Media Accelerator Driver for Mobile Report

Report Date:  04/08/2010
Report Time[hr:mm:ss]: 01:12:35
Driver Version:  6.14.10.4926
Operating System:  Windows XP* Professional, Service Pack 3 (5.1.2600)
Default Language:  English
DirectX* Version:  9.0
Physical Memory:  1014 MB
Minimum Graphics Memory: 8 MB
Maximum Graphics Memory: 128 MB
Graphics Memory in Use: 11 MB
Processor:  x86 family 6 Model 28 Stepping 2
Processor Speed:  1599 MHZ
Vendor ID:  8086
Device ID:  27AE
Device Revision:  03

*   Accelerator Information   *

Accelerator in Use:  Mobile Intel(R) 945 Express Chipset Family
Video BIOS:  1533.0
Current Graphics Mode: 1440 by 900 True Color (60 Hz)

*   Devices Connected to the Graphics Accelerator   *

Active Monitors: 1
Non Active Notebook Displays: 1

*   Monitor   *

Monitor Name:  Plug and Play Monitor
Display Type:  Analog
Gamma Value:  2.20
DDC2 Protocol:  Supported
Maximum Image Size: Horizontal: 16.0  inches
   Vertical:   10.0  inches
Monitor Supported Modes:
640 by 480 (60 Hz)
640 by 480 (67 Hz)
640 by 480 (72 Hz)
640 by 480 (75 Hz)
720 by 400 (70 Hz)
800 by 600 (56 Hz)
800 by 600 (60 Hz)
800 by 600 (72 Hz)
800 by 600 (75 Hz)
832 by 624 (75 Hz)
1024 by 768 (60 Hz)
1024 by 768 (70 Hz)
1024 by 768 (75 Hz)
1152 by 864 (75 Hz)
1152 by 870 (75 Hz)
1280 by 720 (60 Hz)
1280 by 960 (60 Hz)
1280 by 1024 (60 Hz)
1280 by 1024 (75 Hz)
1280 by 1280 (60 Hz)
1440 by 900 (60 Hz)
1440 by 1440 (60 Hz)
1440 by 1440 (75 Hz)
Display Power Management Support:
Standby Mode: Supported
Suspend Mode: Supported
Active Off Mode: Not Supported
Raw EDID:
00 ff ff ff ff ff ff 00 04 72 4f 00 cd 35 80 90
08 13 01 03 68 29 1a 78 ca 80 c5 a6 57 49 9b 23
12 50 54 bf ef 80 71 4f 81 40 81 80 81 c0 81 00
95 00 95 0f 01 01 9a 29 a0 d0 51 84 22 30 50 98
36 00 98 ff 10 00 00 1e 00 00 00 fd 00 38 4c 1f
50 0e 00 0a 20 20 20 20 20 20 00 00 00 fc 00 41
63 65 72 20 58 31 39 33 57 0a 0a 0a 00 00 00 ff
00 4c 44 57 30 44 30 31 36 38 35 30 32 0a 00 a7

*   Notebook   *

Monitor Name:  Digital Flat Panel (1280x1024)
Display Type:  Digital
Gamma Value:  3.54
DDC2 Protocol:  Supported
Maximum Image Size: Horizontal: Not Available
   Vertical:   Not Available
Monitor Supported Modes:
1280 by 1024 (60 Hz)
Display Power Management Support:
Standby Mode: Not Supported
Suspend Mode: Not Supported
Active Off Mode: Supported

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