Uh... well... I used SP for 2 years... but now that I donwloaded the new version of SP, I founded a bug...
On SketchUp 8 Pro, when I use the Joint Connector, in SketchyPhysics 3.2, the cursor turns white somehow, when it should be black. When I hold the CTRL key the plus (+) mark does not appear near the cursor...
And so, connecting joints don't work anymore.
I tried to follow the message of NotSoNaff, but nothing works.