My Screen is making a high pitched squeeking noise.

I will turn my screen on, and I am getting picture on it just fine. After 10-30 minutes of use on the monitor, it will start to emite a high pitched squeeking noise. I have had this problem consistantly for a year now, and I have discovered many things about this noise. 1. The noise is caused by the power cable not being pushed in enough. I tried taping the power cord in, but it slips out, maybe less then a fourth of an inch, and starts making the noise again. I tried pushing in the screws as far as I can, but it doesnt seem to be enough. 2. The noise is a high pitched noise. As people age, their senses worsen. This sound is such a high pitched sound, that any person usually over the age of 30 cannot hear it. Many children use a ringtone called a "Misquito" which makes a noise so high pitched that only people under 30 can hear. This noise coming from my screen must be making a noise of the same frequency or pitch. 3. I have tried auto adjusting my screen multiple times, but it hasn't helped. When I turn the brightness down, the noise is lower, when I turn the brightness up, the sound is more high pitched. 4. The power strip ( the cord that goes into the wall and can have several cords plugged into it at once) is not the problem. I called Westinghouse tech support, and they said that the problem could be the power strip. Its not. I have caled Westinghouse tech support twice now, and both times they told me the same two things. Auto adjust the screen and try a different power strip. Neither worked. I am open to suggestions.