Thank you all for the thoughts.
Hadn't thought of something as simple as torque or even how the plugs were handled. The plug other than being separated looked quite normal in it's burning.
I'm going to look a bit more closely at the the other 3 plugs and see what they tell us now that I know I may have a problem.
I went onto the NGK web site and they had a few other ideas, most of which will be quite time consuming at best and probably more expensive to resolve.
Here's the link if any one is interested.
This is the problem page.
http://www.ngksparkplugs.com/tech_support/spark_plugs/p5.asp?mode=nml
This is the beginning of the write up.
http://www.ngksparkplugs.com/tech_support/spark_plugs/index.asp?mode=nml