Display toggle & external display not working

I'm trying to use an external display as the primary monitor for my XP AAO. I hooked up the monitor, and I can use it as an *extended* display, but when I select the box to use it as the primary display, the external monitor goes black. I realize that Fn+F5 should toggle through all the display possibilities, but when I press Fn-F5, the little horizontal window with four display choices flashes on the screen and then goes away when I release the Fn key.

Any idea where I'm going wrong on this?

 

I've found a workaround to the non-functioning Fn+F5 key: right-click on the desktop and use the Intel Graphics Properties and Graphics Options settings to set the display as desired.

It would be nice to have the toggle working properly, though.

 

you need to install this to get the F keys to work. go here and click on MS XP > Launch Manager

http://support.acer-euro.com/drivers/no ... e_110.html