How do i fix problems with macbook pro and logic 9 electrical noise?

I have a very annoying problem when i am trying to record music, i know plenty of people have also had this problem but as i have many of the solutions already in place to fix the problem , i am still confused as to why its still there; I am using logic 9 express on a macbook pro 2.4 GHz, i have the macbook pro connected to an 8 track behringer mixer connected via USB cable, between the usb port on the laptop and the mixer there is an A-D converter, of which the mixer and A-D converter are connected via two red and white audio cables. Coming out the mixer i have 2 x Rokit 6 KRK monitors, and also a headphone adaptor unit so multiple people can listen in at once. I also have an external screen connected to the mac. the mac power cable, mixer and monitors and screen are all connected to two separate extension leads placed parallel to each other, in which multiple combinations have been made with the powersockets to try and get rid of the noise, none of which have worked when the mac is running with everything plugged in and turned on, i can put the speakers up full and get nothing but a clear speaker hiss which is obvioulsy ideal for audio recording, but as soon as i open up logic express this awful noise starts, a really high pitched siren sound that doesn't go anywhere. Ive noticed as well that when i try and connect a jack plug/ usb plug cable into the mac and open up logic this noise is still there, even when i take the mac away from everything else and just use the jack plug on its own, very confused here, any suggestions???

Are you using any type of pre-amp with filter?

Related articles

How do you get sound from PS3 if you use a monitor with DVI instead of HDMI?
Which one of the following is an example of computer output?
What is the difference in LCD monitors?
Prenatal heart monitors?
What is a good LCD monitor for a Mac?

Today a base stuffing of desktop personal computers - microprocessors, system payments, memory, graphic accelerators and other allow to achieve improbably powerful indicators of productivity. It is interesting that according to researches, the average user uses possibilities of modern personal computers only half or even less.