Monitor has wavy lines....

I have a Latitude E4300 with a E/Port. The monitor is a Dell E198FP with a Analog connection when connected to the E/Port analog port the monitor comes up with a series of wavy lines all thur the screen. After a few minutes it gets really bad to look any longer. I have tried updated drivers and still no results in resolving this issue. If I remove the monitor and use the port on the laptop itself I have no problem. I have also used other Dell monitors 1703FP and they all work fine. Anyone have the same problems.