> This is probably because, on your laptop, you installed Java3D as an
> installed extension (libraries in the ext directory of the JVM), which means
> they are 'natively' seen by all Java applications.

Hey, now we are getting somewhere !
On my laptop the installer placed the java3d jars in my 
Java\jre6\lib\ext folder and everything was good.
On my desktop the jars were placed in my Java\jdk1.6.0_32\jre\lib\ext 
folder and that was not sufficient for eclipse.
After I copied them into the Java\jre6\lib\ext folder, the error message 
disappeared on my desktop.

Problem solved, many thanks !