I think a good first step is to take a battery powered radio in abd check various orientations relative to the computer. I listen to AM talk at lunch time with my little Walkman part way into my top desk drawer. All the way out and I get the noise from the desktop. All the way in and I block reception. Moving the radio around the case can give you an idea of where the leakage is coming from. You could try to improve the RF shielding and grounding in the case. Any exterior plastic that doesn't have a metallic coating inside would be suspect. But using the little radio to find a sweet spot should help. Some buildings pretty severely attenuate radio signals and the station received signal strength relative to the noise amplitude has a great effect too.
Joe
