VGA cable filter

It sounds like a ground loop issue.  Do you have access to a plug adapter like this?



ACS100.jpg

Another way you could try this would be to try to cover the ground point on your ac adapter (with thin electrical tape or something similar) and plug it in the wall.  Given that the electrical tape doesn't tear and keeps the plug from getting that ground connection... then you should get the same result if the plug above.  

Hi - thanks for the info - that plug adapter you show the picture for, can you tell me what its called so I can do a search for it?

Thanks
Andy

http://www.summitsource.com/grounding-adapter-3prong-to-2prong-ac-wall-outlet-polarized-electrical-power-grounded-grounding-adapter-3-prong-outlet-plug-to-2-prong-ac-ground-wire-plug-adapter-part-905100-p-8800.html

it is a 3 TO 2-PRONG AC ADAPTOR ,
See: http://www.allelectronics.com/make-a-store/category/910/A.C.-Plugs-Sockets/1.html
Wes

As an additonal explanation of what you are experincing see:
http://www.jmkfilters.com/faq.htm#EMI_filter
It is called:  Electromagnetic interference, EMI, is any undesirable electromagnetic emission or any electrical or electronic disturbance, man-made or natural, which causes an undesirable response, malfunctioning or degradation in the performance of electrical equipment.
So although what has been suggested may work a better fix would be to add an EMI Filter.
See: X10 Pro Plug-in Filter Module XPPF , If above method doesn't work then this should,
Avalaible at Amazon for $19.90 : http://www.amazon.com/X10-Plug-Filter-Module-XPPF/dp/B0002M5OJI
 
Wes