Now have output on VGA monitor but VLC movie window is blank
 

With thanks to all who have helped I now have all screen output on both the laptop screen and the external VGA Monitor. However when I play a movie with either Movie Player or VLC the window on the VGA monitor is blank surrounded by GUI menu items while the window on the laptop screen has the full movie displayed.
I am running Debian Lenny on a Dell Latitude laptop.
Any help much appreciated.
Thanks
Tony

Possibly VLC is configured to use a Xv overlay for output. Many video cards/drivers only support one such overlay, and in your specific case it's on the laptop display. It happens just the same on my 'el-cheapo' no-name SiS 671 laptop. The SiS 671 chipset only supports one video overlay, and if I move any Xv window to the second monitor the video display will be blank (although GUI items will show).

Possible solutions:
- Use an utility (specific to your video card make/model/driver, in my case it'd be SiSCtrl if I were to get it to compile on Ubuntu Jaunty) to set the video overlay to the secondary display (or, it may involve editing xorg.conf manually).
- Use another display output method. I haven't used VLC for a while but I'm sure it supports other methods (OpenGL, software, etc). It's trial-and-error here - see what works for you.

Hope this helps.