Windows 7: Extended desktop - unable to save display settings?

Hi, I wonder if anyone here can help me?

I have an Asus X5DC laptop with wondows 7 home premium 32bit OS. I just tried updating the driver for my SiS mirage3 graphics card in an attempt to extend desktop into dual monitor mode.

I updated the driver, restarted the computer and everything seemed fine. On the Windows load up screen I get a display on both the laptop screen and the external screen. But then when windows loads up, the display on my laptop screen switches off and only the external one remains. No matter what I do in display settings it will only recognise the external monitor, [although monitor 1 is there, it's just greyed out]. Whenever I try and change it to anything else apart from 'display desktop on monitor 2 only' I get the message 'unable to save display settings'.



To make matters even worse, when I unplug the external, the resolution box is greyed out and stuck on 800x600.

Anyone have any suggestions on how I might fix this? Is it fixable?

Many thanks