When using a projector with a laptop, you may find that some resources (typically video) will display on the laptop screen, but are represented by a black rectangle on the projected image.

The cause of this issue is generally a lack of resources on the laptop - either video memory, or processor cycles, whilst attempting to perform a very demanding task - that of displaying video on both devices at the same time.

There are two possible solutions.

• Switch to a single display output - i.e. the projector (this will typically be identified as a 'CRT').
  
• Open a new instance of Windows Movie Player before launching your program. This may permit dual display of the video resource.

Usually, the f5, f7 or f8 key on the laptop keyboard has symbols on it that indicate video display switching - for example on an IBM laptop, the Fn and f7 keys display video in a cycle between LCD (the laptop screen), CRT (the external display), and LCD & CRT concurrently.

e.g.  press the Fn button and the relevant Function button e.g. f7:

 

Some more modern laptops also require the external port to be activated through the display control panel. You should refer to the documentation that accompanies your laptop for specific advice, or contact the manufacturer for updated drivers.

LCD = Liquid Crystal Display - a flat panel screen - usually the main screen for a laptop.

CRT = Cathode Ray Tube - a large box-shaped monitor screen.

VGA = Video Graphics Array - a standard output for a computer display (also SVGA, XVGA)

Laptops often include an external VGA port to permit the use of a larger monitor - this is frequently a CRT display, but in schools a data projector is typically connected to the same socket and fulfils the same purpose. Laptops are more prone to this particular issue as they tend not to have dedicated hardware assigned for display purposes, rather they share memory and processor tasks with the rest of the PC requirements.