Hi Ed,
Thanks for the response. Whenever I use a GET eg. SPI_GETSCREENSAVERACTIVE the function works fine. It is only when I try to change a parameter with a SET action eg. SPI_SETSCREENSAVERACTIVE that it fails. The code example tries to reset the current screen saver active state, on my machine the screen saver is active therefore the call using SPI_SETSCREENSAVERACTIVE the param has to be 0.

Thanks again
Ray