Press the Aspect button on the remote control to select a different image apsect ratio.
Press the Esc button on the remote control to cancel the E-Zoom function.
Check your computer display settings to disable dual display and set the resolution within the projector's limits. See Supported Video Display Formats.
Check the resolution assigned to your presentation files to see if they are created for a different resolution than you are projecting in. See your software documentation for specific information.