no hardware acceleration when only secondary monitor being used.?

I have a thinkpad t60. The notebook lcd is a 14" running at 1400 x 1050. I have a second display which is a 24" widescreen at 1920 x 1200. When I run both screens, I have hardware acceleration enabled on both.

I go to dxdiag and display 1 and display 2 both have directdraw and direct3d enabled and happy.

If I disable the notebook LCD (or close it) and use only the external, hardware acceleration is disabled. Both directdraw and direct3d are disabled, and the enable button is greyed out. Any idea or fix? I got a wall mount for the 24" so I can use it alone, but now, to play HD videos and stuff, I have to keep my laptop LCD on so that I get H/W acceleration on the external screen.
Sorry correction : Direct3d is alright - AGP texture acceleration and directdraw are the ones with trouble - they both say 'Not Available'

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