Problem with on-board graphics and 2x HD7590

I was mining litecoin with 2xHD7590 and decided to enable on-board graphics. Then nothing worked. The output from cgminer -n was as follows:

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\Miner One>cgminer-3.0.0-windows\cgminer.exe -n
[2013-05-07 20:44:05] CL Platform 0 vendor: Advanced Micro Devices, Inc.

[2013-05-07 20:44:05] CL Platform 0 name: AMD Accelerated Parallel Processing

[2013-05-07 20:44:05] CL Platform 0 version: OpenCL 1.2 AMD-APP (1124.2)

[2013-05-07 20:44:05] Platform 0 devices: 2
[2013-05-07 20:44:05] 0 Tahiti
[2013-05-07 20:44:05] 1 Tahiti
[2013-05-07 20:44:05] CL Platform 1 vendor: Intel(R) Corporation

[2013-05-07 20:44:05] CL Platform 1 name: Intel(R) OpenCL
[2013-05-07 20:44:05] CL Platform 1 version: OpenCL 1.1
[2013-05-07 20:44:05] Platform 1 devices: 1
[2013-05-07 20:44:05] 0 Intel(R) HD Graphics
[2013-05-07 20:44:05] Failed to ADL_Adapter_ID_Get. Error -1

[2013-05-07 20:44:05] Failed to ADL_Adapter_ID_Get. Error -1

[2013-05-07 20:44:05] ADL found less devices than opencl!
[2013-05-07 20:44:05] There is possibly more than one display attached to a GPU

[2013-05-07 20:44:05] Use the gpu map feature to reliably map OpenCL to ADL

[2013-05-07 20:44:05] WARNING: Number of OpenCL and ADL devices did not match!

[2013-05-07 20:44:05] Hardware monitoring may NOT match up with devices!

[2013-05-07 20:44:05] 2 GPU devices max detected
[2013-05-07 20:44:05] USB all: found 6 devices - listing known devices

[2013-05-07 20:44:05] No known USB devices

Question: Can I disable platform 1? If not, can anybody suggest a work-around, other than disabling on-board graphics. I have tried various permutations of --gpu-map but nothing works. Any help appreciated.