Hi Hannsen,
I'm so sorry that I didn't respond to you earlier. I started a response, but I must have forgotten to hit "Submit".
There is one more thing I can think of to try. In addition to deleting the com.google.sketchuppro.plist, could you also delete the com.AtLast.sketchup.plist (assuming you have one). Does that help?
If not, contact the technical support folks at Google using http://sketchup.google.com/gsu6/support.html.
Are you, by any chance, using a localized version of the product? I guess that could be another potential source of the problem.
Best,
Tricia