There is a shadow or double image on the screen

Extension cables, docking stations and longer cables may be prone to ghosting, lines, double images, or poor focus. The improper shielding of the extension cables will cause a shadowing or ghosting effect. This improper shielding causes a mismatch of the input impedance between the video card, the video cable, and the monitor/projector. If you need an adequate extension video cable, please contact ViewSonic Parts Department. Additional contact information is available at our Contact Us page.

In addition, if using a switch box or low quality cable, these two items will also cause signal degradation. Check the video cable to make sure all the pins are in good condition. Test the monitor on a different computer.