Sony Monitor & G4 Difficulty


For the past couple of weeks when I turn my computer on the monitor will have a message that comes up briefly that says no input and then will go blank. I read somewhere that removing the cable and taking a pencil eraser across the prongs (on both ends ) to remove any corrosion might fix the problem. It seemed to work a couple of times and then would work after restarting the computer. Now it won't come on at all. When it did work the picture was perfect so I suspected that the cable might be the culprit. However after testing on another computer it worked perfectly.

What are other possible causes for this problem?