Heavy white lines accross the screen

Question

The monitor has heavy horizontal white lines across the screen. The desktop behind the lines shows up in double. The problem would occur occasionally and currently it has this condition all the time with either the VGA or DVI cable. I've tried different cables, computers, video cards and nothing seems to cure the problem. The monitors is 5 years old. What should I do?

my monitor displays heavy multi colored lines in the screen..i tried it on the other pc and it worked out normally..maybe the problem is inside my cpu(system case)..the multi colored lines is visible but the desktop and pictures are also visible..