Are you on Windows?
You could try registering the SketchupViewer.dll- LO probably can't find it.
Open a DOS box, and cd to here-
C:\Program Files\Google\Google SketchUp 6\LayOut
or where your layout.exe is installed.
Then do-
regsvr32 SketchUpViewer.dll
This should popup a dialog saying succeeded. If it doesn't say succeeded, then reinstalling is best.