There's a great book about grounding and shielding:
"Grounding and Shielding Techniques in Instrumentation" by Ralph Morrison.
http://www.amazon.com/exec/obidos/ASIN/0471245186/qid=1116000890/sr=2-1/ref=pd_bbs_b_2_1/102-4413716-9718501
It goes into all the problems in great detail, clearly written. Of course, the comment in the lab when I bought it 20 years ago was, "and you know, he actually *reads* this stuff". But it's a topic that anyone who uses electronic instrumentation *has* to be aware of.
John Weeks
WaveMetrics, Inc.
Phone (503) 620-3001
Fax (503) 620-6754
www.wavemetrics.com