This is to do with the way you have previously installed SketchUp.
If you did not select the SketchUp-installer exe's icon and right-click and choose 'run as administrator', then you can get permission issues, even if you yourself have 'admin-powers'.
Can you reinstall SketchUp this way ?
If not, then try this: find the main SketchUp.exe in the Program Files subfolders...and right-click it > Properties > Compatibility > Always run this program as an administrator...
Any help ?