External monitor on Asus Eee PC problem

I have an Asus Eee PC, with an external Asus display. The display adapter in Device Manager says Intel Graphics Media Accelerator 3150. I have Windows 7 Professional loaded on it. The drivers are the latest from Asus' website.

The problem is that if the monitor is plugged in when the computer boots up, I see POST on it, but after that, nothing. Fn-F8 won't help, neither will the Graphics Adapter settings, or even unplugging and re-plugging the monitor.

But if I boot up with the monitor disconnected, and then plug it in, it works OK.

Any ideas? Thanks!