Use the SystemParametersInfo function's undocumented SPI_SETSCREENSAVERRUNNING UINT _Junk; // turn off ctl-alt-del SystemParametersInfo(SPI_SETSCREENSAVERRUNNING,1,&_Junk,0); // ... do stuff? like what? // turn on ctl-alt-del SystemParametersInfo(SPI_SETSCREENSAVERRUNNING,0,&_Junk,0);