I have a Philips 109s 19" monitor at home that under certain screen resoloutions makes a really really high pitched "iiiiiiiiii" sound that gives me a shocking headache after about 20 mins.
Does anyone have any idea what it might be, or how I can stop it (apart from change the res)?

For some reason at 1024x768 in windows it doesn't do it, but at 1024x768 in Linux it does...

It also does it at lower res's as well...