resultion switching errors

I'm trying to create a fullscreen display at a set resolution and am changing the display resolution. I use:

DEVMODE dmScreenSettings;								// Device Mode

		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));	// Makes Sure Memory's Cleared

		dmScreenSettings.dmSize=sizeof(dmScreenSettings);		// Size Of The Devmode Structure

		dmScreenSettings.dmPelsWidth	= width;				// Selected Screen Width

		dmScreenSettings.dmPelsHeight	= height;				// Selected Screen Height

		dmScreenSettings.dmBitsPerPel	= bits;					// Selected Bits Per Pixel

		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

		// Try To Set Selected Mode And Get Results.  NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.

		ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)
 

The resolution changes but weird errors occur. If I switch to 640x480 the mouse pointer cannot move to the lower right area of the screen (it's as if the mouse area is smaller than the resolution). If I switch to 1024x768 the screen displays down and to the left by about 400 pixels So what's the stupidly obvious error I'm making this time? [edited by - damocles on July 22, 2003 12:48:48 PM]